390 [July, 



hind the neck, which is followed by other similar rings at regular distances 



throughout the length of the body, to the number of about sixteen. A narrow 



median dorsal white line, commencing at the head, and two lateral ones, one 



on each side, communicating at the neck, also extend throughout. Length, 3 



inches ; breadth, at the middle, 0.08 inch. On weedy sand in the circumlit- 

 toral zone. 

 Hab. Cape of Good Hope, at Simon's Bay. 



25. Polia rhomboidalis. Convex, largest anteriorly, of a pale reddish color, 

 with darker sub-margined longitudinal stripes. Head narrower than the body, 

 rounded in front ; neck slightly marked. Eyes in four clusters ; with four ocelli 

 in each cluster, arranged at the angles of a diamond-shaped area. Tbe clusters 

 of the posterior pair are much the smaller, and are placed in the dark spots 

 forming the commencement of the longitudinal stripes. Length, 1 inch : breadth, 

 0.05 inch. Found in the littoral zone. 



Hab. Australia, at Port Jackson. 



26. Polia grisea. Elongated, subcylindrical, of a grey color; head distinct, 

 subtriangular, much narrower than the body, and separated from it by a well- 

 marked neck. Eyes in four clusters ; two irregular rows on each side of the 

 head to the number of twenty more ; while on each side of the neck there is an 

 elongated, oblique, reddish spot, with two or three ocelli along it3 outer edge. 

 Length, 0.8 inch. Found on sand-fiats in the litteral zone. 



Hab. Coast of Virginia, at Norfolk. 



27. Tetrastemma insicum. Minute, slender, convex, broadest behind the 

 middle ; head with the eyes distinct, and with a lateral fold between the ante- 

 rior and posterior pairs, and one also behind the posterior pair. Color pale- 

 brownish. Length, 0.4 inch ; breadth, 0.025 inch. On weedy sand in the 

 circumlittoral zone. 



Hab. Cape of Good Hope, at Simon's Bay. 



^ 28. Meckelia olivacea. Slender, convex above, especially anteriorly where 

 is also the greatest breadth ; head with a longitudinal slit which extends far 

 down each side, and is covered by a slight vertical notch at the anterior ex- 

 tremity ; genital opening large, on the lower surface of the neck, just behind 

 the termination of the lateral slit. Color anteriorly very dark greenish, or oli- 

 vaceous ; posteriorly a much paler green, Length, 3 inches ; breadth, 0.1 

 inch. Common in sandy bottoms in the circumlittoral zone. 

 Hab. Cape of Good Hope, at Simon's Bay. 



GEPHYREA. 



29. Phascolosomum noduliferum. Sub-fusiform broad, terminating in a 

 point posteriorly, of a pale brownish color; surface with numerous hard, dark- 

 brown, large, elevated tubercles, which are uniformly scattered, and extend much 

 beyond the arms toward tbe proboscis, around the base of which they become 

 smaller. Proboscis smooth, except near its extremity, where it isannulated with 

 narrow, crowded, delicate, black rings, which are seen by means of a magnifyer 

 to be composed of minute echinulations. Mouth with two clusters of short ten- 

 tacles or fimbriations, of different lengths. Color pale brown. Length of the 

 body, 1.15 ; breadth, 0.4 inch. Under stones in the littoral zone. 



Hab. Australia, at Port Jackson. 



30. Phascolosomum semicinctum. Of a light brown color, with bluish re- 

 flections ; surface very smooth in appearance, but showing, under a magnifyer, 

 a few minute, black, granulations, distantly scattered. Proboscis very long, an- 

 nulated with narrow black rings towards the extremity ; mouth with two tufts 

 of blunt tentacula. Found in holes in coral, etc., in the coralline zone. 



Hab. Cape of Good Hope, in False Bay. 



In both these species the generative organs are placed one on each side of 



