ANATOMICAL LASD^IARKS. 95 



by the dotted line, is the Ctl. thyroidea. lu man it forms the mesal 

 projection known as "Adam's apple." Just ventrad of it in the 

 figure, but caudad in the normal position of the parts, is the ring 

 shaped Ctl. cricoidea. Each thyro-hyal segment of the Os hyoides 

 is directly connected with the larynx by a small Ctl. arytenoldea, 

 one of which is indistinctly shown in the figure at the dorsal (really 

 cephalic) end of the prolongation of the Ctl. cricoidea. The epi- 

 glottis is seen projecting just dorsad of the thyro-hyals. 



ANATOMICAL LANDMARKS. 



§ 225. During dissection and exjDerimentation it is often de- 

 sirable to determine the lines and limits of incisions, or to ascertain 

 the location and outline of parts which are obscured by the skin or 

 other soft parts. The elevations and depressions which may serve 

 as guides are called anatomical landmarks. 



The landmarks here described sliould be carefully studied, first upon the prepared 

 skeleton by the aid of figures and descriptions, and then upon the entire cat by the aid of 

 preparations of the soft parts, and frozen sections and dissections. 



Most of the landmarks are more easily recognized upon the living or freshly killed 

 animal, but they sliould be sought also during the continuance of rigor mortis, and upon 

 specimens hardened by alcohol. Finally, their recognition should be practised also with 

 the eyes closed. 



Whoever intends to perform experiments should become sufficiently intimate with 

 some cat to be permitted to manipulate all the accessible parts. The late Prof. Jeffries 

 Wyman once told the senior author that in Paris he lived in the same house with Straus- 

 Durckheim ; and that the indefatigable felitomist would sometimes sit by the hour holding 

 a cat, and passing his fingars from point to point over the muscular elevations, the joints 

 and other bony prominences with which his mind was occupied at that time. 



The landmarks form three groups, mesal somatic, lateral so- 

 matic, and memhral. 



§ 226. Mesal* Somatic Landmarks — Crista lamhdoidalis — 

 (Fig. ^<6). — Promiuent as is this crest upon the prepared skull, it is 

 by no means easy to find upon the entire animal. The cervical 

 muscles just caudad of the occiput are very firm and compact, so 

 that the change of substance is not very marked to the touch. 

 The crista, however, is nearly in a line with the most caudal con- 

 vexity of the ears, and may be more distinctly felt during alternate 

 ventiiduction and dorsiduction of the head. 



§ 227. Spina Neuralis Axialis — The axial spine — (Fig, 30). — The 

 somewhat sharp caudal projection of this spine may be felt at the 

 dorsimeson between the cervical muscles 3-4 cm. from the Crista 

 lambdoidalis, and not far from the scapulae. 



