摘要:

During the second decade of the 19th century, eight authors described 24 recent and 26 fossil species ofConus, bringing to 486 the number of proposed species‐group names in the genus through 1820. This study analyses these nominal species, as well as three described by Perry in 1810, and evaluates the status of each. Most of the European Tertiary species described by Brocchi in 1814 and some of those described by Borson and Schlotheim in 1820 are valid. Megerle von Mühlfeld in 1816 and Dillwyn in 1817 each described a valid recent species. All otherConusspecies names introduced during the period are synonyms of previously or contemporaneously described species ornomina dubia.Type specimens of 23 species, including one neotype, are known to exist today. At the present time 148 valid species ofConusare recognized from the species‐group names introduced between 1758 and 1820. Of these, 131 are extant and 17 are known only as Tertiary fossils. In addition, six otherwise valid species, three recent and three fossil, were described but were given preoccupied n

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01806.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The structure of the hyoid arch of the ptyctodontCtenurellais described and discussed with reference to theories of jaw suspension in placoderm fishes. It is concluded that primitive placoderms had a modified hyoid arch but that the hyomandibular took no direct role in supporting the jaws. The relationships of ptyctodonts are discussed and it is concluded that they are placoderm fishes. Several different classifications of placoderm fishes are evaluated and are shown to be weakly based, chiefly because of lack of precise knowledge of character distribution. An attempt is made to produce a classification by using a simple cladistic computer analysis. The result highlights homoplasy in character distribution amongst traditionally recognized placoderm groups.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01807.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Intraspecific variation inPolydora ciliata(Johnston) was assessed on the basis of evidence from morphological characters, which were studied by scanning electron microscopy. Differences were observed between populations of P.ciliatawith respect to the setae of the fifth modified segment and in the caruncle. Two other species, namelyP. ligniWebster andP. limicola(Annenkova), were also studied in order to assess interspecific variation. The two forms of P.ciliata, that is boring and non‐boring, were found to be different morphologicall

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01808.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The effect of irregular photoperiods on various growth parameters and oviposition of a tropical freshwater pulmonate,Bulinus tropicus, has been investigated. Over a period of 6 weeks the growth (measured as an increase in wet weight) of juvenile snails was unaffected by transfer to reversed and to random non‐circadian light‐dark regimens, although oviposition was considerably retarded in the latter experimental group and its time of onset was delayed relative to the control group held in a 12 h light‐12 h dark regimen. Snails exposed to constant light grew more, and their oviposition rate (number of eggs snail‐1week‐1) was equal to that of the control group, but these two parameters were found to be considerably reduced in snails kept in constant darkness. The food consumption, assimilation and food conversion efficiency of snails in random and reversed light‐dark regimens were comparable to the control groups, whereas animals in constant light ate more and those in constant darkness ate less. The weekly mean assimilation rate and food conversion efficiency were greater in the latter gro

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01809.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01806a.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY