1901.] ANATOMY OF COGIA BREVICEPS. 113 



papilla is as follows: — it is more or less circular in transverse 

 section ; its epithelium consists of about three layers of cells, the 

 most superficial of which are well-defined, refringent, and somewhat 

 cuticular iu aspect. The nuclei of these cells are not much more 

 flattened than those of the deeper cells, which are arranged with 

 the long axis parallel to the surface ; the upper ones, however, are 

 smaller and take the stain less deeply than the others. The bulk 

 of the wall of the papilla is formed of concentric fibres of elastic 

 connective tissue, which is somewhat looser externally than 

 internally. Below this comes white fibrous tissue penetrated 

 by numerous capillaries and small blood-vessels. The centre of 

 the papilla is occupied by a cavity (*? lymphatic) in which an 

 unstainable coagulum was noted : it is lined by a layer of flat 

 cells. 



Towards the lower end of the papillae the white fibrous tissue 

 becomes more abundant, and passes gradually into that of the 

 membrane lining the chamber, while the elastic tissue decreases. 



I have no suggestions to make as to the functions of these 

 peculiar structures. 



The muscles that act upon these chambers in the Delphinidse 

 have been fully described by Sibson, Murie, and others : un- 

 fortunately the head of my specimen was too much injured to 

 allow me to trace them out in Cogia. 



Remarks. — A comparison of the foregoing account of the 

 spiracular sacs in Cogia with that given by various authors for 

 members of the family Delphinidse brings out several differences 

 which seem to be of importance. 



In the Delphinidse the single blowhole opens into a " vestibule " 

 or spiracular cavity, which is in communication with (1) the two 

 narial canals, and (2) from four to seven diverticula, that are 

 known as " spiracular " pouches or sacs. (The nomenclature of 

 the parts is iu need of revision.) 



In Cogia the " vestibule" is extremely reduced ; indeed it seems 

 rather to be represented by the upper, slightly dilated end of the 

 left narial canal, into which the small right narial canal has come 

 to open, having pushed its way across the middle line in order to 

 reach it. The ' ; spiracular chambers " are here dilatations in the 

 course of the right narial canal : they are unpaired and are not 

 diverticula. 



This being the case, it seems impossible to homologise them 

 with the functionally similar pouches in the Delphinidse. At the 

 game time I must confess that the only accounts to which [ have 

 access are those of Sibson [10], Marie [4,5,6 j, and Struthers [12|,in 

 add it ion to t hat by Huxley iii his ' .Manual." Of these, the firsl gives 

 a detailed description of the relations of the various sacs to the 

 " spiracnlar vestibule*" and to the narial canals; and he gives 

 figures of actual dissections in illustration thereof. Murie deals 

 chiefly with the muscular arrangements, and discusses the 

 homologies of the apparatus with structures presenl in other 

 mammals; while Struthers's account i~> in a footnote, and merely 



Paoo. Zooi. Soo.— 1901, Vol. II, No.VUI. 



