320 MES. L. J. WILSMORE ON ZoANTliE/E FROM 



meet with an instance in any Zoanthesc (5). Oar knowledge of the reproduc- 

 tive systems ot" the genus Zoantlms is, however, still incomplete, since several 

 species have been described which contained no gonads. 



Z. sandvicensis and Z. similis are undoubtedly closely allied. The two species 

 resemble each other externally in general appearance and in the character of 

 the coenenchyme ; and internally, in the general structure of the colunm-wall, 

 mesenteries and tentacles. They differ in shape and size and in several 

 anatomical points, such as structure o£ the disc, thickness of the column- 

 Avall, character of the sphincter muscle, and number of mesenteries and 

 tentacles. These latter number from .50-56 in the smaller form, Z. similis, 

 and from 34-40 in Z. sandvicensis. 



The sphincter muscle of Z. similis is intermediate in structure between 

 that of Z. sandvicensis and of Z. cJiierchice, von Heider (6). It differs from 

 the former in arrangement, shape and number of cavities and their contents 

 (PI. 44. figs. 3, 9), and from the latter in that it does not lie nearer the 

 endoderm, but occupies the whole width of the mesogloea and the cavities, 

 which are much more numerous and more closely packed than in Z. cliiercldce ; 

 all contain free muscle-cells. 



I have had some difficulty in deciding wdiether the two forms Z. sandvicensis 

 and Z. similis should be regarded as one or two species, and have decided 

 on the latter alternative chiefly from a consideration of the value placed on 

 the sphincter muscle for specific purposes within the genus. The other 

 anatomical differences give weight to this decision. 



ZOANTHUS PIGMBNTATUS, Sp. n. (Pls. 43, 45. figS. 11-15.) 



Form. (PI. 43. fig. 11). — The polyps, which are distinctly club-shaped, 

 present a very irregular appearance both in size and grouping. Column and 

 capitulum alike are much wrinkled transversely, only a few fine ridges are 

 present at the opening in the sv/ollen capitulum. The coenenchyme forms a 

 flattened expansion, from which little groups of polyps arise. This may have 

 formed a network, but the pieces collected are not sufficient to decide the 

 point. Stolons are also present, and occasionally a stolon is found passing 

 from one polyp to another above the level of the coenenchyme proper. New 

 ]Jolyps arise either directly from the new unpigmented coenenchyme, or by 

 budding from the column of an older individual. In this latter case, the 

 budding takes place near, but not at, the base of the column, and the piece of 

 the column below the budding forms a common stalk for both polyps (PI. 43. 

 fig. 11). In this way are formed the stems with two branches which arise 

 here and there from the coenenchyme. 



Colour. — Greyish brown in spirit : a few of the polyps and patches of the 

 coenenchyme are a light sand-colour. Reddish-brown spots surround the 

 orifice of the capitulum in many individuals. 



