vii RHODOPE VERANII 281 



W. Salensky. Etudes sur le dtvcloppcment du Vermet. Arch. Biol. Tome VI. 



1887. 

 Beitrdge zur Entwickelungsgeschichte der Prosobranchier. Zeitschr. f. wiss. 



ZooL 22 Bd. 1872. 

 P. B. Sarasin. Entwickelungsgeschichte der Bithynia tentaculata. Arb. Zool-Zoot. 



Instit. Wurtzburg. 6 Bd. 1882. 

 Paul and Fritz Sarasin. Aus der Entwickelungsgeschichte van Helix Waltonii. 



Ergebn. Nat. Forsch. Ceylon, 1884-1886. 1 Bd. Wiesbaden, 1888. 

 P. Schiemenz. Zusammenfassende Darstellung der Beobachtungen von Eisig, 



Rouzaud, Jourdain, Brock, etc., uber die Entwickelung der Genitalorgane der 



Gastropoden. Biol. Centralblatt. 7 Bd. 1888. 

 C. Schierholz. Ueber Entwickelung der .Unioniden. Denkschr. Akad. Wien. 55 



Bd. 1888. 

 F. Schmidt. Beitrag zur Kenntniss der postembryonalen Entwickelung der Najaden. 



Archiv. fur Naturgeschichte. 51 Jahrg. 1885. 

 M. Ussow. Untcrsuchungen uber die Entwickelung der Cephalopoden. Arch. Biol. 



Tome II. 1881. 

 L. Vialleton. Rccherches sur les premiere phases du dtoeloppement de la Seiche. 



Annal. Sc. Nat. (7). Tome VI, 1888. 

 Wladimir Wolfson. Die embryonale Entwickelung des Lymnceus stagnalis. Bullet. 



Acad. Imp. Sc. St. Petersbourg. 26 Jahrg. 1880. 

 H. E. Ziegler. Die Entwickelung von Cyclas cornea, Lam. Zeitschr. f. wiss. Zool. 



41 Bd. 1885. 



Appendage. 



Rhodope Veranii. 



This small animal (circ. 4 mm. in length) is long and spindle-shaped, and out- 

 Avardly bilaterally symmetrical. The body epithelium is ciliated all over. There 

 is a dermo-muscular tube, inside which, embedded in the connective tissue (paren- 

 chyma), are found numerous irregularly shaped calcareous particles. 



Alimentary Canal. The mouth lies at the anterior end of this canal, and leads 

 into a wide buccal or oesophageal cavity, into the first part of which two acinose 

 salivary glands open. A radula and jaws are wanting. A narrow oesophagus con- 

 nects the oesophageal cavity with the tube-like mid-gut, which runs through the 

 whole length of the body. The midgut possesses a well-developed muscular wall, and 

 is continued anteriorly, above the point where the oesophagus enters it, in the form 

 of a diverticulum, which runs forward over the brain. There is no separate digestive 

 gland. The right side of the mid-gut gives rise to a short, thin, ciliated rectum, 

 which runs through the posterior third of the body, and opens through the anus to 

 the right. 



The nervous system consists of two pairs of ganglia lying so close together above 

 the oesophagus as almost to form one mass, and of one infra-cesophageal ganglion, 

 which lies somewhat asymmetrically to the left. The two ganglia of each of the 

 upper pairs are connected by transverse commissures, and the posterior dorsal pair 

 with the lower ganglion by two connectives which embrace the oesophagus. Two 

 lateral nerves which run backward are the most strongly developed. They arise out 

 of the posterior upper pair of ganglia, close to which lie a pair of eyes arid a pair of 

 ciliated auditory vesicles, each of the latter containing an otolith. 



Genital Organs. Rhodope is hermaphrodite. The gonads consist of about 20 

 follicles which lie ventrally in the median and posterior thirds of the body ; the 

 anterior follicles produce eggs and the posterior spermatozoa. The ducts of all the 



