78 



the viscero-bi'aiu-hial connot-tive a very short distance and tlien enters the l)ra,n- 

 chial heart. It is possible that this nerve arises from the visceral ganglion , not 

 from the branchial . and it is also possible that this nerve , not one from the 

 splanchnic ganglion, su])plics the systemic heart. 



Thk Sense Organs. 



The organs of special sense are the statocysts, the eyes, and the organ 

 which is probably olfactory in fnnction. The last is an area of colummar epithel- 

 ium situated in the concavity at the lower end of the "olfactory crest" and 

 innervated by a nerve from the pedal ganglion. 



The Statocysts. 



The statocysts of the Cephalopoda have been described by Hamlvn-Harris 

 and, although he did not have this species before him, his description of 

 the statocysts of Loligo vulgaris holds true for this species. The statocysts lie 

 in the skull below the visceral, and behind the pedal ganglion. The cavity of 

 each is 2 or 3 mm. in diameter and 3 or more mm. in length. They are side 

 by side and are separated by a thin cartilaginous septum. Twelve papillae project 

 into the statocystic cavity. These are situated as follows , passing backward from 

 the first, near the front end, to the last, near the back end of the cavity: 

 The first postero-median papilla. 

 „ second „ „ „ behind the preceding. 



„ first median „ above the preceding. 



,, antero-median „ 



„ first posterior „ 



anterior „ j The first anterior, the second median 



„ second median „ [ and the second posterior papillae are 



posterior „ ) included in the same cross section. 



?) 



first external „ ( 



These papillae are side by side and 

 . the first which is bent upward is poste- 

 " ^6C0"d " » ) rior to the second which is erect. 



„ third posterior „ This begins as a ridge on the thick- 



ened posterior part of the septum, runs 

 outward and backward, and ends in a 

 posterior papilla. 



