278 Introductio7i to Animal Morphology. 



mantle or beside the anus, and a second, surrounded 

 by a sphincter, into the pericardium. This organ 

 may be hyaline (Cymbulia, Clione), or thick, con- 

 tractile (Styliola), or soft, spongy, and glandular 

 (Hyalea, Cleodora). Beside it in Pneumodermon is a 

 wheel-like ciliated body of unknown function. 



There is a circum-cesophageal nerve- ring with two 

 large, confluent, sub-oesophageal ganglia, joined by a 

 commissure over the oesophagus ; from these pass 

 branches to the epipodia and to the body wall. A 

 sympathetic ring with one or two pair of ganglia sur- 

 rounds the intestine lower down. In Pneumodermon, 

 Clione, &c., there are two or, usually, three, rarely 

 four, pair of united ganglia, the hypopharyngeal bear- 

 ing otocysts, with mulberry-like otoliths. These 

 ganglia consist of oval or unipolar nerve cells. The 

 head bears paired, large (Theceurybia), or small 

 (Hyalea) tentacles, which are rarely seated on the 

 front of the fins (Limacina and Styliola virgula), or 

 absent (Halopsyche). There are three pair of feelers 

 in Clione australis. Anterior feelers in Clionopsis are 

 supposed, but without sufficient reason, to be olfactory. 

 Eyes represented by pigment specks are found on the 

 visceral sac of Hyalea. Similar masses with lens-like 

 bodies lie on tentacle-like processes on the neck in 

 Cleodora and Styliola acicula, &c. 



The single, lobed, hermaphrodite gland lies behind 

 the stomach and beside the heart in the visceral sac : 

 its duct dilates into a seminal vesicle, receives the 

 duct of an albumen gland, and a small receptaciiliuii 

 semtms, and then ends in a vagina, in front of which 

 is the eversible imperforate penis. The outer part of 

 the gland produces ova, the inner, spermatozoa ; but 



