REVISE THE GROUP AND TO DETERMINE ITS GEOGRAPHICAL RANGE. 347 



Species 14. Thalassemia erythrograrrvmon. Max Miiller. Plate XXXIII. Fig. 4. 



Greef. Acta Ac. German, Vol. xli. Pt. n. 1S79, p. 147. 

 Von Drasche. Verh. Ges. Wien, Vol. xxx. 1881, p. 624. 

 Sluiter. Natuurk. Tijdschr. Nederl. Ind. Vol. xliii. 1884, p. 58. 



Length of body, 8 — 16 cm. Length of proboscis about one-third to three-quarters of 

 body-length. 



Colour of proboscis, on the outer dorsal surface bright green, on the ventral, yellow, 

 with a violet line on each side. The hinder end of body is violet, and longitudinally 

 grooved, the grooves being light or dark red, according to the state of contraction. The 

 Bourbon specimens in life were described as green, with red longitudinal stripes and 

 white proboscis. The colour of Dr Willey's specimen is described in Part I. of this 

 article. 



Longitudinal muscles, arranged in 14 bundles. 



Nephridia, three pairs, with spirally coiled internal openings. 



Anal trees, very thin, brown. 



A rectal diverticulum is present. 



Locality. Red Sea ; Isle of Bourbon ; Billitou, Malay Peninsula ; China Straits, 

 New Guinea. Amongst coral. 



Species 15. Thalassema exilii. Fr. Miiller. 



Lampert. Zeitschr. wiss. Zool. Vol. xxxix. 1883, p. 341. 



The details of this species are furnished by Lampert from four specimens in the 

 Berlin Collection, labelled " Thalassema exilii, Fritz Miiller, Brasilien, Desterro, Fritz 

 Miiller." The description of the author of the species, if one existed, appears to be lost. 



Length, 2'6 cm. The body expands posteriorly. 



Colour, brown in spirit specimens. 



Papillae, scattered irregularly from the middle to the posterior end of the body, but 

 they are most strongly aggregated round the middle. 



Longitudinal muscles, 8 — 10 bundles. 



Nephridia, two pairs. The internal openings are folded and crinkled, not spirally 

 twisted. 



Anal trees, small. 



Locality. Desterro, in Brazil. 



Species 16. Thalassema faex. Selenka. 



Selenka. Challenger Reports, Vol. XIII. Pt. xxxvi. 1885, p. 7. 



Length of body, 4 cm. when contracted. Diameter, 15 cm. 

 Colour, whitish and the skin is smooth. 

 Papillae, indistinct and scattered. 

 Longitudinal muscles, undivided. 



