TUNICATA. 299 



The tentacles, however, are inure numerous than in P. viridis, and are arranged 

 distinctly in three rows (tig. 8). The zooids are of unusually large size, and the 

 stolon is encrusted with sand. The atrial aperture is distinctly five-lobed. This 

 species thus presents a combination of characters seen separately in several other 

 species, and does not agree entirely with any. I have pleasure in associating this 

 new species with the name of my colleague in the pearl fisheries investigation, 

 Mr. James Hornell, F.L.S., who was with me on the barque " Itangasami-Poravi " 

 on April 2, 1902, when the specimens were collected. 



Ecteinascidia thurstoni, Herdman. Plate I., figs. 18 to 23. 



This species was originally found in the Gulf of Manaar by Mr. Edgar Thurston, 

 and was described by me in 1890* and named in honour of its discoverer. The type 

 specimen is in the Government Central Museum, Madras. The species has since been 

 recorded from Bermuda by Van Name, and from the Bay of Djibouti, Somali-land, by 

 Gravier. 



The colonies which I now refer to this species were collected on Aripu coral reel 

 on March 18, 1902, and are attached to fragments of a massive sponge. One colony 

 (fig. 18) has about 14 Ascidiozooids, another has two or three only, the third has 

 half a dozen large and small with a few buds in addition ; and there are also a few 

 loose Ascidiozooids (fig. 19) detached from colonies. 



All the Ascidiozooids, although transparent, are of a slightly pink colour, like the 

 sponge they grow over ; but it is possible this may be a post-mortem effect produced 

 by staining with the pigment dissolved out from the sponge. The largest Ascidiozooid 

 measures 8 millims. x 3 millims. a more usual size is 5 millims. in length. In 

 Thurston's specimens the Ascidiozooids were rather larger, and ranged from 7 millims. 

 to 2 centims. in length. Otherwise the appearance of the colonies is very similar, and 

 the internal structure is also very much the same in the two cases. In our specimens 

 the branchial aperture may be seven-lobed and the atrial six-lobed (fig. 23). The 

 meshes of the branchial sac generally contain three stigmata ; four is the number given 

 in the description of E. thurstoni. The rest of the branchial sac and the dorsal 

 languets (fig. 21) seem to agree well ; but the tentacles are not so numerous and 

 closely placed in our present form (fig. 20), where there seem to be about 60 in all, of 

 three sizes. Possibly the rather smaller size, fewer stigmata and less closely placed 

 tentacles may all be co-related characters indicating merely a younger stage in growth. 

 The course of the alimentary canal and gonads (fig. 22) seem alike in the two cases. 



Ecteinascidia (? Rhopalopsis) solida, n. sp. Plate I., figs. 15 to 17. 



External Appearance. Shape, a cylindrical finger-like mass somewhat bent at 

 the free end, attached posteriorly by a broad base and with both apertures at the 

 anterior end. Surface smooth ; size about 2*5 centims. X 1 centim. 



* 'Trans. Biol. Soc, Liverpool,' vol. v., p. 144. 

 2 Q 2 



