摘要:

Variation in morphology of beaver cheek teeth has been examined in respect of ontogeny, geographical variation and geological time. When the effects of ontogeny are taken into account, certain patterns of dental variation are found to be restricted in space and time. An isolated loop of enamel ubiquitously present in the lower third molars of European beavers from the present interglacial seems to be a “new” acquisition which is lacking in Recent Siberian and North American beavers, as well as in Western European specimens from earlier interglacials.Whilst the genetic basis of such morphological details is presumed rather than established, they may be helpful in tracing past population movements and are also of potential stratigraphic importance. Changes in range associated with Pleistocene climatic oscillations have led to the “sudden” appearance of this and other castorid dental characters in the Western European fossil record. The morphological discontinuity in the fossil record should be taken as evidence of climatic change rather than evidence for the operation of a certain pattern of ev

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01089.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The genusPilgnmella, known from the medial Eocene of Pakistan and northwest India, is a primitive perissodactyl, not an artiodactyl as previously identified. Upper cheek teeth ofPilgrimella, when compared with those of primitive representatives of the Equoidea, Brontotherioidea, Chalicotherioidea, Tapirioidea and Rhinocerotoidea, suggest, however, thatPilgnmellacannot on present evidence be referred to any of the five accepted perissodactyl superfamilies.Pilgrimellamay represent a short‐lived and hitherto unknown perissodactyl lineag

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01090.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The form and location of the scales of salticid spiders, as revealed by light and scanning electron microscopy, provide useful diagnostic characters for the separation of species, the assignment of species to genera, and a further understanding of the relationships between salticid genera. Partly on the basis of distinctions provided by scale structure, the new genusPlatycryptus, type‐speciesAranea undataDe Geer, 1778, is defined.Metaphidippus vitisCockerell, 1894, is placed in the genusSassacusPeckham, 1895, andParomaevia michelsoni(Barnes), 1955, is returned to the genusMaevia. The placement ofEris, Hentzia, Icius, Metaphidippus, Phidippus, andSassacusin the subfamily Dendryphantinae is substantiated;TutelinaandZygoballusare added to this group. On the basis of common scale structure,Evarcha, Habrocestum, Menememerus, Phlegra, Platycryptus, andSitticusare tentatively assigned to the subfamily Habrocestinae. Scales ofAnasntis, Corythalia, Cosmophasis, Hyllus, Marpissa, Metacyrba, Pellenes, Plexippus, Salticus, Sarinda,andThiodinaare also describe

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01091.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Variation in shell shape and penis morphology ofLittorina rudisMaton is examined using data from all parts of Britain. The shell shape variation within populations of L.rudisis shown to account forLiltorina patulaJeffrys at the only site where the latter species was recorded. In addition, the shell shape of I,.rudisvaries with exposure, individuals on exposed shores having a relatively larger aperture than those on sheltered shores. Wave action and desiccation are considered the most likely factors maintaining this variation. The penis morphology of L. rudis varies within and between shores to an extent that renders the use of this character invalid for distinguishingL. patulafromL. rudis.The radulae of adults ofL. rudis, L. patulaandLittorina nigrolineata(Gray) are similar in structure having blunt cusps, whilst adultLittorina neglectaBean and juvenileL. rudishave pointed cusps. The possibility of a neotenous origin ofL. neglectafromL. rudisis discussed. On the evidence presented here it is suggested thatL. patulamust be regarded as a synonym ofL. rudis.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01092.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Several recent studies have focused on the ability of the gekkonidPtychozoon lionatumto parachute, utilizing its enlarged lateral body folds. Little attention has been paid, however, to the evolution of such behavious and here several aspects pertaining to the origin of parachuting are integrated. Behavioural shifts and morphological modifications are considered together and evaluated in the light of ecological information. It is apparent that certain behavioural shifts were the precursors of subsequent morphological changes. The structural design of the body folds is also considered in relation to parachuting behaviour and both the gross morphology and histology are shown to be significantly modified to permit effective parachuting. The absene of musculature in the lateral body flaps of geckos is confirmed and a model for the integration of the various factors involved in effective parachuting is presented. Here the importance of the “structure‐function” and “habitat‐behaviour” sets are emphasized together with their new interrelationships when a protoadaptation becomes

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01093.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

A new species of pycnogonid,Endeis pictasp. nov., is described from the coast of Ghana, occuring in aBalanus tintinnabulumfouling community on a ship's hull. The species is close toE. straughaniClark.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01094.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Growth allomentry in the development of the brine shrimpArtemia salina(L.) was studied. Body width and abdomen length show a negative allometric relation to body length (k=0.35 and 0.72 respectively) over th eight instars studied. Antennule length shows a negative allometric relation in respect to body length, with a change in the value of the growth constant at Instar Five from 0.31 to 0.75. Thoracic limb length shows a high positive relation to body length (k=3.0) until Instar Six, when a negative allometric phase (k=0.4) follows. A change in the sign of the growth constant from positive (k=0.45) to negative (k=‐1.4) is noted for the length of the 2nd antenna in relation to body lengt

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01095.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Karyotype studies support the view that modern genera of the family Ctenodactylidae originated in Africa. Karyotype differences between the genera are less obvious than morphological differences but coincide in relatingMassoutieratoFeloviaand deriving this line from thePectinator‐like ancestor which, in turn, was closely related to aCtenodactylusancestor. 43% of the chromosomes are standard throughout the family; 25% seem to be very susceptible to fragmentation, translocation and inversion. These changeable chromosomes are the only ones that show differences in their G‐band patterns. The ctenodactylid karyotype resembles caviomorph karyotypes in its NF, predominantly metacentric chromosomes and in its nucleolar organiser, or marker, chromoso

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1979.tb01096.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY