REVISE THE GROUP AND TO DETERMINE ITS GEOGRAPHICAL RANGE. 351 



Species 25. Tkalassema neptuni. Gaertner. Plate XXXIII. Figs. -1 and 5. 

 Greef. Acta Ac. German. Vol. xli. Pt. n. 1879, p. 145. 



Length of body, expanded 1", contracted, '5". Length of proboscis, three or four 

 times length of body when extended. 



Colour of proboscis is golden yellow, of the body orange yellow, the middle of the 

 body is pink, and behind it is white. 



Longitudinal muscles. Like Lampert I can find no mention of the condition of 

 the longitudinal muscles in this species, in the literature of the subject, but I have 

 satisfied myself by the dissection of some specimens from Plymouth, that these muscles 

 form a continuous sheath and are not divided into bundles. 



Nephridia, two pairs, with their internal openings spirally twisted. 



LOCALITY. English Channel, South Irish Coast. In holes in the rocks, cavities in 

 red sandstone, etc. 



Species 26. Thalassema pellucidum. Fischer. 



Fischer. Abh. Ver. Hamburg, Veil. xm. 1895, p. 19. 



Length of body averages 2 - 5 cm. Length of proboscis, 6 mm. 



Colour. The young tonus are light yellow, the older forms are bluish. 



Papillae small and distributed over all the body, but on the pointed posterior end 

 they are bigger and more crowded. 



Longitudinal muscles, 13 in number, visible through the skin. The space between 

 neighbouring bundles is broader than the bundles. 



Nephridia, two pairs, with spirally twisted internal openings. 



Anal trees about one-fourth as long as body, with single — not branched — diverticula, 

 each ending in a funnel. 



Locality. Whydah, \V. Africa. In mud at 5 and 5| fathoms. 



Species 27. Thalassema semoni. Fischer. 



Fischer. Zool. Forschungsr. in Australien etc., Semon, Vol. v. Pt. in. 1896, p. 338. 



Length of body, 5*5 cm. in larger of two specimens. The proboscis was absent. 

 Colour of body, bluish-grey. 



Papillae uniformly distributed, almost touching one another. 

 Longitudinal muscles in a continuous sheath. 

 Nephridia. two pairs, with spirally rolled internal openings. 



Anal trees, thin and brown, longer than half the body-length and attached by 

 muscles to the body-wall. 



Locality. Amboina. 



w. in. 48 



