摘要:

Summary.1The hyoid apparatus and tongues of fifteen reptiles are described and discussed.2The patterns formed by the transverse muscles of the throat are classificatory importance, as are also the intrinsic muscles of the tongue. The study of these muscles throws new light on the position of the families Iguanidae and Chameleontidæ.3The hyoid apparatus and its muscles exhibit variations too numerous to provide data of taxonomic importance. The gular structures, as well as protrusible tongues, are aided by specially modified devices of the hyoid apparatus.4The mechanism of the protrusible tongues of reptiles is described.5The hyoid apparatus and the muscles of the tongue and throat co‐operate in making the buccal cavity an active agent in the respiratory mechanism of most reptil

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00821.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00822.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00823.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00824.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

Summary..A comparison inCentetes ecwudatusand related forms of each tooth with those adjacent to it has led to the following conclusions:–1In all Zalambdodonts there is in the cheek region a progressive simplification on either side of an anticlinal tooth.2Posteriorly, in the upper jaw, the simplification involves principally a reduction of the posterobuccal part of the tooth, including the posterobuccal root and the corresponding cusps on the crown, and a shortening of the posterior edge of the tooth.3Anteriorly, in the upper jaw, the lingual and posterobuccal roots approach and unite, the main cusp takes up a central position, the lingual ledge moves to the posterior end, the buccal cusps are reduced to a posterobuccal swelling near the base, the anterior ridge of the main cusp disappears, and the anterior cusp becomes rudimentary.4These sequences, occurring in all species, affect different teeth in different species. The anticlinal tooth can vary from pd4to m2, and the amount of difference between adjacent teeth differs according to the species.5The simplification sequence is similar in the premolars and the milk‐molars, but there are differences between the two series, the premolars being usually larger and broader, with blunter main cusp and smaller accessory cusps.6The molars resemble the milk‐molars rather than the premolars, and must be regarded as the posterior members of the milk‐molar series.7At the posterior end of the lower jaw there is often no reduction process, and the anterior reduction takes a different form in the lower jaw from the upper. The metaconid merges into the slopes of the protoconid, the paraconid takes up an anterior position and becomes low, the hypoconid and entoconid disappear, and the hypoconulid remains as a small posterior cusp.8In both jaws the anterior cheek‐teeth are formed on the same plan. There are two roots, a central main cusp, and small anterior and posterior accessory cusps.9The canines and incisors are modifications of this basic form: in the canine the roots are usually united, the main cusp is very large, and the other cusps are small or absent; in the incisor the cusps are flattened and more equal in size. Additional cusps sometimes appear, especially a labial cusp in the lower jaw and an anterohngual cusp in the upper jaw.10Variations in the shape of one tooth are frequently correlated with corresponding variations in other teeth. With regard to variation and evolution, teeth are part of a system, and not independent units. The enlargement of the permanent canines in the maleCentetesis accompanied by a reduction of the anterior premolars.11Similarity of pattern of adjacent teeth is almost certainly indicative of homology rather than of convergent evolution. This makes possible a return to the premolar‐anatomy theory in its simple form,i. e., the homo‐logizing of molar cusps by discovering the mode of transition from the simple anterior tooth to the molar. The similarity of the anterior teeth in both jaws makes possible a morphological comparison of upper and lower molars.12Such a comparison indicates that(a)paracone=protoconid=main cusp of the canine and other anterior teeth, (6) the lingual side of the upper tooth=the buccal side of the lower one andvice versa, and (c) the trigonid is not a more ancient part of the lower molar tha

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00825.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00826.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

Summary.1Vanessa urticxhas six Malpighian tubules, three on each side which open into the colon by a common duct. Between the tubules proper and the common duct is a small‐celled undifferentiated region known as the imaginal ring or interstitial ring.2The posterior ends of the tubules enter into close association with the wall of the rectum forming the rectal plexus.3In theembryo(ofPieris hrassicse)the tubules arise in association with the proctodeum. During the first half of the embryonic period the tubules grow by active cell division, but there is no differentiation. During the second half of the embryonic period differentiation takes place, but no new cells are formed.4In thelarva(ofVanessa urticse)the tubules grow by an increase in the size of their constituent cells. The nuclei are rounded at first but become palmate and finally much ramified. The nuclei of the cells of the rectal plexus remain rounded throughout larval life. In no parts of the tubules proper is there any cell division.5The common duct increases in size by a continuous enlargement of its constituent cells. There is no cell division. This mode of growth is similar to that of the hind‐gut.6The interstitial (imaginal) ring continues cell division throughout larval life. As a formative region, however, it is relatively inactive and adds only a few cells to the tubules proper and common duct. It appears to be a relic of the embryonic blastopore, which fails to differentiate completely but retains to a slight extent its capacity for producing endoderm internally (tubules proper) and ectoderm externally (common du

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00827.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00828.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00829.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1937.tb00830.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY