122 OKHAMANDAL MARINE ZOOLOGY REPORT— PART II 



mentj but a more complete account of the spiculation seems desirable to accompany 

 the illustrations, especially as I omitted before to mention two types of spicule which 

 occur both in Carter's type and in the Ceylon and Okhamandal specimens. These 

 are the small, palmate anisochelse and the small, slender sigmata. I think I 

 must have regarded these formerly as merely young forms, but I do not think 

 that that view can be accepted. There are, then, no fewer than seven different 

 kinds of spicule in the sponge, and the constancy in form and size in all the 

 specimens I have examined, including the type, is very remarkable. 



1. Tylostyli (Fig. 4a), of the usual Esperella type, generally slightly crooked ; 

 size about 0-3 by 0-009 mm. (much more slender forms also occur). 



2. Large, broad, palmate anisochelse (Figs. 4&-46"), about 0-049 mm. in 

 length by 0-022 mm. in greatest width from one lateral palm to the other. 



3. Small palmate anisochelse (Figs. 4c, 4c'), about 0-02 mm. long by 0-008 mm. 

 in greatest width. 



4. Minute palmate isochelse (Figs. 4td, 4d'), resembling those of Clathria, 

 about 0-012 mm. long. 



5. Large, stout sigmata (Figs. 4e, 4e'), probably all really more or less 

 contort, with abruptly recurved and very sharply pointed ends ; length in a 

 straight line from bend to bend about 0-094 mm., thickness about 0-0054 mm. 



6. Small, slender, contort sigmata (Fig. 4/) ; length in a straight line from 

 bend to bend about 0-033 mm., thickness about 0-0013 mm. ; but variable in 

 dimensions. 



7. Slender toxa (Fig. 4^^), gently curved like a parenthesis mark ; length about 

 0-065 mm., thickness about 0-0013 mm. ; sometimes arranged in toxodragmata. 



Pending a much-needed revision of the esperelline sponges I adhere to the 

 genus Esperella for this species, but, apart altogether from the question whether or 

 not that name should be replaced by Mycale, it seems probable that the genus 

 will have to be split up in the near future. 



I have already [1905] pointed out the close resemblance of the characteristic 

 large anisochelse of this species to the corresponding spicules of Esperella simonis 

 Ridley and Dendy [1887], from Simon's Bay, Cape of Good Hope. It is obvious 

 that the two species are closely related, but there are certain well-marked 

 differences in the spiculation. Chief amongst these are the absence from the 

 spiculation of E. simonis of the minute, palmate isochelse and of the small, slender 

 sigmata, both of which are very abundant in E. plumosa, which has an extra- 

 ordinarily full complement of spicules. Other differences concern the size of the 

 spicules and the shape of the toxa, which are much more strongly arcuate in 

 E. simonis. 



Previously known Distribution. Mauritius and Mergui Archipelago (Carter) ; 

 Ceylon (Dendy). 



