253 



form represented in Chall. Report, PI. LXV, fig. 4) are also common. 

 Besides these there occurs in tolerable abundance a very remarkable 

 form of rosettes. From a spherical centre, about 0.046 mm in diameter, 

 there radiate in all directions innumerable filamentous rays, that may 

 attain a length of 0.44 mm, each terminating in a small cup -shaped 

 disc with serrated edge. The entire rosette is thus sun-shaped and 

 almost I mm in diameter. 



The dermal skeleton consists of a subdermal network composed 

 of strands of diacts and of autodermal pentacts, rarely tetracts, with 

 rays 0.12 mm in average length and spinous only at ends. The gastral 

 skeleton is similarly constituted with this difference that the auto- 

 gastrals are mostly hexacts and rarely pentacts or tetracts. These are 

 of about the double size of dermals and spinous all over except at the 

 central node. 



Rossella longispina n. sp. 



The specimen before me is a pear-shaped, thick- walled sac-nar- 

 rowed below to a stalk-like base, where it is torn off. Length 51 mm; 

 greatest breadth 37 mm. The osculum at the top is oval, 14 mm by 

 7.5 mm; its edge thin and simple. The external surface is uneven on 

 account of low conical elevations, from the apex of which strong diact 

 prostalia project in an obliquely upward direction, some to a length 

 of 30 mm or more. There are also some small pentact prostalia, which 

 are nothing else than protruded hypodermals. The simple gastral ca- 

 vity is lined by a smooth gastral skeleton. 



Attached to the diact prostalia there are two very small indivi- 

 duals of the same species. Whether these arose as buds from the large 

 individual or not, cannot be ascertained. 



The principal parenchymals are exclusively diacts of various size. 

 Parenchymal microsclerae of three kinds: rough micro- oxyhexacts 

 and their derivatives, viz., oxyhexasters and semi-oxyhexasters (dia. 

 0.097 mm) that are of such general occurrence in Rossellidae ; 2)disco- 

 hexasters (dia. 0.07—0.13 mm, of the form of fig. 10, PL LVII, Chall. 

 Report) with short principals thickened at end, whence arise 4 — 6 slen- 

 der terminals ending in a 6-teethed disc; 3) micro- discohexasters of 

 the well-known form. 



The hypodermal frame-work is composed of strands of diacts and 

 of pentacts. The latter may, as already noticed, protrude beyond the 

 dermal surface as prostalia. Their paratangential rays (1.5 ram or less 

 in length) are finely rough all over and either form right angles with 

 one another or are pushed , as it were, to one side as in R. antarctica. 



