516 EDITH M. PRATT. 



margin of the capitulum the siphonozooids are extremely numerous, a contrast to Sarco- 

 phytuvi, in which the autozooids are most numerous in this position. The stomodaeum 

 (fig. 14, s.) is short and straight, averaging "26 mm. in length. The siphonoglyph is well 

 marked. 



As a rule, the length of a siphonozooid varies according to age, the young siphonozooids 

 are extremely short, but the older ones may extend for quite a considerable distance into 

 the interior of the colony. The diameter of a siphonozooid is greatest at the surface, and 

 gradually decreases inwardly. Some distance below the surface the cavity is sometimes so 

 narrow that, but for the presence of the dorsal mesentery filaments, it might be easily 

 mistaken for an endodermal canal. Sooner or later a siphonozooid terminates posteriorly in 

 the endodermal canal, from which as a bud it originated. The keyhole shaped mouth 

 aperture of the stomodaeum, with well-marked ciliated siphonoglyph, and the eight mesenteries 

 of a siphonozooid, may be easily distinguished in surface view (fig. 13). 



IV. GENUS SCLEROPHYTUM. 



Sclerophytum, gen. nov. (PL XXVIII. fig. 8, PI. XXIX. figs. 15—18, Pis. XXX. and XXXI.). 



In the Introduction to this paper (pp. 504^ — 5) I have given the most important reasons 

 for the establishment of this genus, and for the inclusion in it of the following species, 

 which have hitherto been attributed to the genus Lobophytum : L. densum = Sclerophytum 

 densum; L. densum, wax. = Sclerophytum, sp. nov.'; L. confertum = Sclerophytum confertum,^; 

 L. marenzelleri = Sclerophytum marenzelleri^ ; L. tuberculosum = Sclerophytum tuberculosum'. In 

 addition to these six new species were collected by Mr Gardiner on the Maldive reefs. 



The genus Sinularia (W. May, 1899, p. 100), which is founded entirely upon the form 

 of the colony and the character of the spicules, cannot be maintained. Further investigation 

 of its single species S. brassica will doubtless result in its inclusion in the present genus. 



Brief Diagnosis of Genus. Colony lobed and sometimes similar in form to Lobophytum.. 

 Corallum often hard and granular (exceptions given in table, p. 531). Colonies usually 

 dimorphic, but the siphonozooids are very minute and exhibit unmistakable signs of degenera- 

 tion. Autozooids are usually smaller than in Sarcophytum, Lobophytum and Alcyonium, and 

 in some cases slightly degenerate. There are two well-marked canal systems, (i) supei-ficial, 

 and (ii) internal. The superficial canals in most species large and numerous, but this system 

 absent or only feebly marked in Lobophytum, Sarcophytum and Alcyonium. The internal 

 canal system is similar in many respects to that of Sarcophytum and Lobophytum, and 

 penetrates down to base of colony. In Alcyonium the internal canal system is not well 

 marked in the deeper portions of the colony. 



Spicules — usually distinct from those of Sarcophytum or Lobophytum; they are generally 

 large and of varied form. Tuberculate spicules occur throughout the genus. Minute clubs 

 and spindles are crowded near the surface, and form a very much thinner crust than in 

 Alcyonium or Acrophytum. 



Great diversity of form is to be found among the representatives of the genus in the 

 collection. The young colonies are more or less mushroom-shaped (fig. 18). Some specimens 

 have a cup-shaped capitulum with marginal lappets — these are usually fairly young colonies 



' These species are not present in the collection. 



