106 Dr. W. A. Herdman. On the Genus Culeolus. [Dec. 8, 



along the ventral edge of the branchial sac. The intestine (i.) runs 

 anteriorly from the stomach for a certain distance, and then, tnrning 

 towards the dorsal region, returns parallel to its first part towards the 

 posterior end, and finally terminates near the posteriorly placed atrial 

 aperture (At). 



Ascidia. Culeolus. 



The annexed diagrams show the relation of the course of the intestine 

 in Culeolus to the arrangement found in Ascidia. The chief difference 

 is that in the latter genns the intestine, after rnnning posteriorly for 

 a short distance, takes a final curve anteriorly, thus making a second loop 

 (2), open anteriorly, which is entirely wanting in Culeolus. The cause 

 of the difference is obviously the position of the atrial aperture (At.) 

 This lies in Culeolus almost at the posterior end of the body, and con- 

 sequently the last part of the intestine runs posteriorly. In Ascidia, on 

 the other hand, the atrial aperture is usually situated near the 

 anterior extremity, therefore the intestine is necessarily twisted for- 

 wards again so that it may terminate near the common excretory 

 aperture. 



All the species of Cideolus are from upwards of 600 fathoms ; five 

 are from over 1,000 fathoms, four from over 1,500, and two from up- 

 wards of 2,000 fathoms. They all belong to the abyssal fauna. 



It is noteworthy that these six species, the only deep-water Bol- 

 teninae, all belong to one genus, notwithstanding their wide distribu- 

 tion in space — one species being from the North Atlantic, two from 

 the Southern Ocean, one from the South Pacific, one from the North 

 Pacific, and one from the centre of the Pacific Ocean on the Equator. 



