T>16 COLLECTIONS FROM THE WESTERN INDIAN OCEAN. 



mentioned by Cartor, 11. cc.) of a fine tricurvate acerate flesh-spicule 

 in addition to an equianchorate. A third species, E. vasiplicata, 

 assigned by Cartor {op. cit. 1882, x. p. 114) to the genus belongs, 

 as I have stated in my report on the Australian collections (Part I. 

 p. 454), not to this genus, but to Echinodictyum, mihi. The genus 

 was not met with by the ' Alert ' on the north and east of Australia, 

 although it is common on the south and south-west (Carter) ; it is 

 a little strange therefore to find the following two species in the 

 western part of the Indian Ocean. 



38. Echinonema, sp. 



A small, irregularly-grown specimen in spirit, consisting of an 

 extended coating base and three low lobes, more or less flattened, 

 two of them uniting with each other. Surface corrugated by low 

 mseandering ridges, giving an irregularly dimpled aspect to the sur- 

 face ; dermal membrane upon the ridges glabrous. Vents small, 

 scattered, oval or circular, -6 to 1-0 millim. in diameter, generally 

 placed on margins or in depressions rather than in the middle of 

 surfaces. Consistence in spirit firm, very tough, elastic ; colour dull 

 umber-brown. 



Main skeleton approximately rectangular in arrangement, the pri- 

 mary fibres being set vertically to the surface, and the secondaries 

 parallel to it, but with their ends curved round to meet the primaries ; 

 fibre very strong, pale to dark amber-yellow in colour : the primary 

 fibres about - 14 millim. thick, and cored for one to two thirds of their 

 thickness by subspinulate spicules ; secondary fibre "07 to '14 millim. 

 thick, either devoid of spicules or cored by at most two series. 

 Dermal skeleton formed by a set of radiating tufts of subspinulate 

 spicules, the bases of the tufts being placed about '25 millim. apart, 

 and the ends of the spicules of the different tufts intercrossing. Sar- 

 code pale yellowish brown, subtran spa rent. Spicules : — (1) Skeletal 

 and dermal subspinulate ; head slight, oval, provided with a few 

 very fine terminal spines ; head of about the same diameter as middle 

 of shaft ; tapering gradually to sharp point ; size '26 by -008 millim. 

 (2) Echinating spined subspinulate ; the head and distal two thirds 

 well spined ; spines strong, sharp, projecting at right angles to 

 surface ; size of spicule "1 by -0085 millim. (3) Tricurvate acerate 

 of sarcode, median curve rather sharp ; size -04 by "001 millim. 

 (4) Equianchorate, navicular, shaft slightly curved ; length of spicule 

 •012 millim. 



Hah. Etoile Island, Amirante group, 13 fms. ; attached to dead 

 coral. 



This species is evidently nearly related to E. typicum and E. an- 

 choratum of Carter, from its resemblance in external form and in 

 spiculation. The structure of the dermal " crust " is essentially the 

 same as that described by me in the nearly allied genus Rlui- 

 phidophlus (see R. arborescens and R. procerus, Part I. pp. 450-1, of 

 this lleport). 



