61 



densely calcified, and so is that portion of the lamina at 

 the junction of the arms. The remainder or posterior 

 part of the bone consists of a very thin plate or lamina. 

 The " inter-clavicle " is called by Owen, Huxley and other 

 anatomists sometimes the uro-hyalf and sometimes the 

 basi-branchiostegal, and it is asserted by Cunningham 

 that these names cannot correctly be applied to it. The 

 term (i.e., "jugular") used by Cunningham is, however, 

 itself inadmissible, since it is liable to be confounded with 

 the jugal or with the jugular plates of " Ganoids " — with 

 the former of which it can have no possible connection. 

 In the Sole, according to this author, it is applied directly 

 to the clavicle and first basi-branchial, and in this differs 

 markedly from the Plaice, Avhere it is placed some dis- 

 tance from both these bones. Its position in the Plaice 

 relative to that of the clavicle is correctly indicated in 

 fig. 8, and it is somewhat further removed from the hyoid 

 arch. Hence, whatever its position in other Teleosts, in 

 the Plaice it is directly connected neither with the clavicle 

 nor with the hyoid. In Sehnsfo/ohns according to >Starks, 

 and in Microijterus according to Shufeldt, what seems to be 

 the undoubted homologue of the " inter-clavicle " articu- 

 lates with the hyoid arch and is called by these iuithors the 

 " uro-hyal.' Cunningham's objection to this term, how- 

 ever, seems to be valid, and hence the provisional name of 

 " inter-clavicle " — a bone with which it may not unrea- 

 sonably be identified. On the other hand its connection 

 in other forms with the hyoid arch indicates that it may 

 have been derived from branchiostegal rays, in which case 

 it may conceivably be homologous with the jugular 



t The supposed resemblance to the uro-hyal of the bird doubtless 

 suggested this homology. Kyle has recently revived this name for the 

 bone, but does not seem to be aware that the terms uro- and glosso-hyal 

 are too often used as synonyms to justify any separation now. In any 

 case, we consider the term uro-hyal quite inadmissible. 



