30 MR. W. F. LANCHESTER OX THE [Jan. 17, 



openings serve to clearly distinguish it, externally, from the latter 

 species, to which it appears at first sight vei-y similar. 



This species, originally known from America, has also been 

 described by Fischer from Madagascar. 



5. SiPUNCULUS BILLITONENSIS Sllliter. 



Natuurk. Tijdschr. ISTed. Ind. xlv. p. 487. 

 Loo. Pemba Island. 



Hah. From eastern reefs in sand near the shore. 

 One specimen. 



G. SiPUNCULUS AUSTRALIS Kof. 



Selenka, tora. cit. p. 90. 



Log. Chwaka Bay, Zanzibar. 



One specimen. 



This specimen, a large one, agrees in all features with Selenka's 

 description, but is without any hooks on the introvert. The 

 presence of hook-bearing individuals in species that normally 

 possess no hooks has already been recoixled, but I am not aware of 

 an instance being known of the opposite phenomenon. That 

 some of the hooks may drop off is, however, recognised, and it 

 would seem that we have here the same occuri'ence cairied to 

 completion, owing either to age or causes that cannot be definitely 

 specified. Of course we may be dealing with a case of local 

 variation, but of this there is no evidence. 



II. Genus Physcosoma. 



7. Physcosoma scolops Sel. & de Man. 



Selenka, tovi. cit. pp. 75-76. 



Loc. British East Africa. 



Hah. Among coral at low tide ; 2 specimens. Muddy shore 

 at low tide ; 1 specimen. 10 fathoms; 4 specimens, 



Loc. Chwaka Bay, Zanzibar ; 1 specimen. 



These individuals correspond with the variety mossamhicense of 

 Selenka and de Man, in which the dark lines bordering the clear 

 spaces in the hooks are curved and not bent at an angle. The 

 accessory process varies, in the hooks of an individual, from being 

 present as a distinct small tooth through intermediate stages to 

 complete absence. 



8. Physcosoma nigrescens Kef. 



Selenka, torn. cit. p. 72. 



Loc. Zanzibar Channel, 5 fathoms. 



One specimen in which, as in Selenka's Mauritius form, the 

 papillse on the base of the introvert are slightly larger than those 

 on the body, and the hooks slightly different. 



Loc. Chwaka Bay. 



One large specimen. The longitudinal muscles do not anasto- 

 mose immediately in front of the anus, but extend a little distance 

 up the introvert. Hooks typical. 



