COLYMBl 389 



semi-ring has the unusual relations shown in the drawing, 

 which are perfectly consistent with the belief that the ring is 

 the second bronchial. The intrinsic muscles are attached to 

 the third tracheal ring in front of the tracheo-bronchial box. 

 The bronchial semi-rings are fairly ossified, but have rather 

 wide membranous interspaces. 



In Podicipes cristatus there is the same failure of the 

 intrinsic syringeal muscles to reach even the end of the 

 trachea, A box is formed by fusion at the end of the trachea, 

 into which it appears to me the first bronchial semi-ring does 

 not enter. The bronchial semi-rings are deeper and closer 

 together, and the whole bronchus is more ossified, than in 

 the last genus. The bronchi, too, are longer. 



In Podicipes cornutus the syrinx is much the same, but 

 of course smaller. The first free semi-ring of the bronchus 

 seems to be No. 2. There is a wider membranous interval 

 between it and the antecedent tracheo-bronchial box than in 

 the last species. 



Tachybaptes fluviatilis (fig. 189, p. 388) has a different 

 syrinx. The last three tracheal rings are only fused in front, 

 though they are closely united laterally. These rings are 

 much ossified. The insertion of the intrinsic muscles is 

 remarkable. They run obliquely forward, converging, to be 

 inserted into the last three tracheal rings. The first bron- 

 chial semi-ring is arched, and ossified in front, where it is 

 fused with the tracheal box ; otherwise it and the succeeding 

 rings are cartilaginous. It is clear, therefore, that the 

 syringeal characters justify the generic distinction here 

 adopted. 



The cervical vertebra are more numerous in the grebes 

 than in the divers ; they are only fourteen or fifteen in the 

 latter, twenty-one in JEchmophorus and Podicipes cornu- 

 tus. Cervical vertebrae 10 to 16 in Mchmophorus ' have 

 a catapophysial canal; on 17 and 18 the hypapophyses 

 are blade-like and enormous ; these processes extend to 

 the very end of the dorsal series. The last cervical and 

 the first three dorsals are fused. There is no catapophysial 



' A canal is nearly formed in Podiceps, 



