508 EDITH M. PRATT. 



of the capitulum, so that the colony retains its mushroom-like form throughout life. In 

 Lohophytum, however, new autozooids are formed from any portion of the capitulum, and 

 growth at the margin where autozooids are fewest is necessarily very slow, consequently as 

 a colony grows it loses its primitive mushroom-shape and assumes a lobulated appearance'. 



1. Sarcophytwm ehrenbergi (PL XXVIII. figs. 1 and 2). Marenzeller, 1886 (p. 3.56, 

 Taf. IX. figs. 3 and 4). 



Four small specimens were taken on the reefs at Hulule, Male Atoll, and two larger 

 incomplete specimens at Goidu, Gorfurfehendu Atoll. 



All the specimens agree fairly well with Marenzeller's description. The margin of the 

 capitulum in young specimens is incurved, rounded and unbroken, in older colonies it is 

 often convoluted. The colour in spirit is light greenish-brown. The autozooids are large 

 and well-marked, and are more numerous round the margin, but this character is not so 

 strongly marked as in tenuis (fig. 9) and latum. 



Autozooids. The anthocodiae of fairly expanded autozooids are about 5 mm. in length. 

 The surface diameter of an autozooid cavity is '8 mm. The tentacles are short and pinnate 

 (fig. 2), and are about 1 mm. in length. Spicules are present in the form of minute, slender, 

 tuberculate spindles averaging "1 mm. in length. These are arranged more or less longi- 

 tudinally on the walls of the tentacles (fig. 2 sp.), and not en chevron as in many of the 

 species. The stomodaeum is very long and much convoluted. The mesenteries are large, the 

 ventral and lateral ones being provided with very stout and rounded mesenterial filaments, 

 which in the preserved condition are much convoluted at the beginning of their course. 

 I have been unable to find reproductive organs in the mesenteries of any of the specimens. 



The siphonozooids are very well marked and extend for a considerable distance into 

 the interior of the colony, but they are not so numerous as in S. latum and many other 

 species. They are regularly arranged in rings round the autozooids, and are most numerous 

 in the middle of the capitulum, where from four to five may be counted in a straight 

 line between two autozooids. The average surface diameter of a siphonozooid is '37 mm., 

 and is greater than in S. glaucum. The stomodaeum may be seen in surface view as a key- 

 hole shaped aperture. Its average length is '32 mm., which is quite twice that of S. glaucum. 

 The eight mesenteries are not so well marked as S. latum. The spicules have been fully 

 described and figured by Marenzeller (1886). They are very abundant near the surface of 

 the colony, but are relatively scarce in the coenenchym. 



Zouchlorellae are present in this as in other species, but I have not been able to find 

 any of the rounded cells with yellow contents which are present in S. glaucum, etc. 



S. ehrenbergi, then, is ' characterised by:^(l) the form and distribution of the spicules 

 which are numerous near the surface, but few in the coenenchym ; (2) the tough, firm texture 

 of the colony; (3) the large size of the autozooids, which have large, stout, rounded ventral 

 and lateral mesenterial filaments; and (4) the clearly defined large siphonozooids, apparently 

 less numerous than in other species, with a long stomodaeum fully twice the length of that 

 of S. glaucum. 



' A young mushroom-shaped colony of Selerophijtum may they can never be distinguished without the aid of a micro- 

 be easily distinguished from Sarcophytum or Lnbophytum by scope, 

 the minute size or absence of siphonozooids. Where present, 



