118 THE VOYAGE OF H.M.S. CHALLENGEE. 



referable to this species. One, which was purchased by Professor Steeustrup at Cette and is 

 probably from the East Indies, bears four fine specimens of the rare Rhizochilus 

 antipathum, Stp. This specimen is 26 cm. high and 41 cm. broad. The stem is strong 

 and the branches are distinctly stronger than the branchlets ; the latter only become 

 reduced to the thickness of the pinnules at the extreme apex of the corallum. Fusions 

 are numerous and extend quite to the apex of the specimen. The branches and their 

 derivatives form flat leaf-like fronds, not all in the same plane, but the subdivisions of 

 each are chiefly in one plane. Part of the reticulum forms a median vertical plate at 

 right angles to the main growth ; I have observed a similar condition in Tylopaihes ? 

 flabellum (Pall.). The other specimen, received through the Museum of Comparative 

 Zoology at Harvard College from Manila, is smaller and does not show such a contrast 

 between the thickness of the branches and branchlets. 



The spines are conical with a sharp apex, and are placed at right angles to the axis ; 

 they are arranged in regular sinistrorse spirals, excepting near the apex of a pinnule. 

 Six longitudinal rows may be counted from one aspect, the members of a row being about 

 two and a half lengths apart. Near the apex of a pinnule they are somewhat triangular, 

 but never crowded and thickened as in Antipathella assimilis. On the older portions they 

 are subcylindrical and more elongate than is shown in PL XII. fig. 3. 



Habitat. — East Indies? (Esper) ; Manila (Mus. Comp. Zool. Harvard Coll.). 



Antipathella assimilis, n. sp. (PI. I. figs. 4-7). 



Corallum forming a flabellate reticulum similar to that of Antipathella reticulata 

 (Esp.), but the lateral branchlets are longer, not arched, and the reticulum is closer. The 

 spines are at first crowded and very irregular in shape ; later they have a blunt apex 

 and are arranged in dextrorse spirals (PI. I. figs. 4, 5, 6, 7). 



The specimen consists of the apical portion of a branch fused with the derivatives of 

 other branches. This specimen is 16 cm. in length and 12 cm. broad. The main branch 

 is 16 cm. long, and gives off numerous lateral alternate branches, about five to a centimetre. 

 Some of these are 6 to 7 cm. long, but most are considerably shorter. A number of them 

 are slender and simple, not over 1 cm. long, and are, in all respects, similar to the ultimate 

 pinnules. Most, however, bear alternate pinnules (3-5 to 1 cm.), the longer of these being 

 again alternately pinnate. The whole specimen extends chiefly in one plane, but a few of 

 the pinnules arise from the antero-lateral margin of the branchlets and thus destroy the 

 uniformity. Some of these are pinnate and have then the appearance of a small frond 

 inserted obliquely into the general mass. The sclerenchyma is dark reddish brown. 

 The pinnules of adjoining branchlets overlap one another and become fused together 

 into a network, and the branchlets derived from one branch, taking a subvertical course, 

 become confluent with others which extend subhorizontally and are derived from 



