摘要:

Material of the fossil holostean genusOphiopsishas been re‐examined. The immediate sister‐group ofOphiopsisis the genusMacreplstiusCope. The latter belongs to the family Caturidae, a paraphyletic assemblage. A new family, the Ophiopsidae, is established here to includeOphiopsisandMacrepistius. Specializations which may relate other caturids to this family are discus

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1975.tb00263.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The Department of Fishery Science requested information on a suitable morphological method to distinguish mature stages of fish. This paper reports a possible technique to specify the stages of maturity of femaleGudusia chapra(Ham.) by two sets of morphometric measurements, CG—Snout vs. CG—Caudal Base and CG—Dorsal Line vs. CG—Ventral Line, on the relative position of the centre of gravity on the surface of the body of the fish. The point of CG changes temporarily towards the anterior and the ventral side of the body to equilibrate the buoyancy of the fish in water because the ovary on growth proceeds and adds weight to those directions, and this shifting causes the variations in the measurements within the set. The “F” value 4.96 shows a significant difference at 1% probability for both the sets of measurements between the three stage‐groups: spent/immature, maturing and mature.SUMMARYSeventy selected fresh adult femaleGudusia chapra(116.0–190.5 mm long with standard length 91.0–153.5 mm) were examined in order to study the position of centre of gravity on the surface of the body and to specify the stages of maturity by means of two sets of measurements, viz., CG—Snout vs. CG—Caudal Base and CG—Dorsal Line vs. CG—Ventral Line. The CG was determined by simple method of suspension and was found to be always below the lateral line within an area of 7 mm vertical × 8 mm longitudinal. It was situated between the 14th and 17th scales on the transverse series from the dorsal line, 1st and 5th from the lateral line.Three stage‐groups of the ovary as spent/immature, maturing and mature were made. The average values of difference of the measurements CG—Snout/ CG—Caudal Base for the different stage‐groups had an upward trend from 11.65 to 18.68mm and that of the measurements CG—Dorsal Line/CG—Ventral Line had a downward trend from 6.24 to 4.46 mm, indicating the gradual shift of the CG as the ovary develops from the imm

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1975.tb00264.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The behaviour of the wild “black” or “house” rat,Rattus rattusL., was studied in an artificial environment, a plus‐maze. The maze consisted of a central nest box and four arms. Food and water were placed at the ends of different arms, and movements of the rats were recorded automatically. A detailed analysis was made of habituation to the artificial environment and of the patterns of activity displayed there. Rats were most active during the dark phase of ‘he light cycle; they displayed a bimodal pattern of visits to and time spent in the arms, with peaks around three hours after lights off and four hours before lights on. Reaction to new objects and places was measured in several ways. The rats usually avoided new objects placed in a familiar area, but showed little hesitation to explore a previously inaccessible area. Rats generally stopped avoiding new objects in the feeding area within one to two days, even when an alternative source of food was available elsewhere. There was, however, much variation.The methods used allow study of two distinct initial responses to novelty, each clearly displayed: (a) withdrawal from a strange object in a familiar place (“fear”), and (b) approach to a newly accessible area (“curiosity”). Behaviour often depends on the interaction between

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1975.tb00265.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

A critical review of the sipunculan genusLithacrosiphon, based on all of the type material and museum specimens with the exception ofL. uniscutatus, results in the combining of nine species into three.L. maldivensiswith its granular anal shield remains unchanged.L. cristatuswith a grooved anal shield and both unidentate and bidentate hooks is redescribed and now includesL. altriconus, L. gurjanovae, L. indicus, andL. odhneri. TheL. uniscutatuscomplex which allegedly has only unidentate hooks is discussed and now includesL. kukenthaliandL. poritidis. This is a troublesome species as the pertinent specimens were either unavailable (L. uniscutatus) or with missing introverts (L. kukenthaliandL. poritidis). An identification key is provided and the several morphological characters used for purposes of identification are reviewed and evaluated.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1975.tb00266.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Frozen and celloidin sections of the cuticle ofPandinushave been examined by means of phase contrast microscopy. The massive cuticle of the pedipalp, and the thinner cuticle of sterna and terga, show a random arrangement of fibres in the horizontal plane, whereas in the cylindrical podomeres of the legs the fibres are parallel and disposed along the length of the podomere. The laminae appear to be composed of horizontally arranged fibres, possibly associated with a laminar membrane. Curved continuous sheets of fibres pass from one lamina to the next through the interlaminar region.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1975.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Rodents are well known for the production of physically quite different audible and ultrasonic cries. Both of these cries are known to be produced in the larynx, but the anatomy of the larynx is practically unknown, it thus being difficult to analyse how the cries are produced. The anatomy of the larynx ofMus musculusis described in detail and is found to be essentially typical of that of other mammals that can fix the thorax and make independent use of the forelimbs. Unlike the larynx of microchiropteran bats, no modifications for ultrasound production are apparent, although the laryngeäl structure is ideal for the production of audible cries. However, the audible and ultrasonic cries differ so markedly that they are unlikely to be produced by the same mechanism. The lack of laryngeal specialization therefore makes the ultrasound production mechanism largely an enigma

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1975.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY