, 8P0NGIIDA. 437 



70. Esperia pellucida. 

 (PiAiB XL. fig. K ; Plate XLII. fig. h.) 



Growth horizontal, spreading over and between stones &o., rising 

 at certain points into slender lobes. Surface even, glabrous. Con- 

 . sistence rather firm and 'brittle. Vents? Colour in spirit pale 

 pink or dirty white, subtransparent. Dermal membrane gela- 

 tinous, transparent, subelastic, firm ; internal structures soft. Main 

 skeleton formed of delicate, widely inosculating fibres 4 to 6 spi- 

 cules broad, soft, branching at obtuse angles. Dermal skeleton 

 consisting of angular meshes formed by distinct straight tracts of 

 spicules, 2 to 4 spicules broad. 



Spicules : — (1) Skeleton subspinulate ; straight or slightly curved ; 

 head marked by a slight and gradual enlargement a little below 

 base ; head round and blunt, diameter less than maximum diameter 

 of shaft ; shaft tapering gradually to sharp point from within about 

 2 to 6 diameters of apex ; size "42 by •0095 miUim. (2) Large 

 inequianchorate ; shaft strong, slightly bent, of same diameter 

 throughout except near the two ends. Large end forming about 

 one third of total length of spicule, diameter about the same as its 

 length. Lateral palms, as seen from front, broad, truncate below, 

 inferior angle projecting slightly ; outer margin slightly reverted 

 throughout ; median palm oval, small ; tubercle distinct, small, 

 pear-shaped ; small end almost truncate above as seen from front, 

 but with the supero-lateral angles sharp, slightly produced upwards, 

 outer margins reverted throughout ; tubercle relatively large, anvil- 

 shaped ; the small end of the spicule is truncate below and about 

 half the diameter of the large end ; length of spicule "l millim. 

 (3) Small inequianchorate ; shaft slender, gradually curved ; large 

 end forming about two fifths of total length of spicule^; lateral palms 

 with sharp inferior angles, being excavated on inner side, outer 

 margin reverted throughout ; tubercle narrow, elongate ; smaller end 

 about half the length of upper (larger) end ; outer margin reverted 

 throughout ; tubercle subterminal, squarish ; end truncate below : 

 length of spicule -032 millim. (4) Bihamate, contort, slender, with 

 wide curve ; size "057 by -0032 millim. (5) Trichites, in bundles 

 of from 20 to 30, with fine points ; size of individual spicules "06 

 by -0015 millim. . 



Hah. Alert Island, Torres Straits, 7 fms. ; bottom sand.' 

 The anchorate of this spicule belongs to the more common of the 

 types occurring in Atlantic and Mediterranean Esperice ; it is, how- 

 ever, larger than most, if not all, and the presence of a second form 

 of inequianchorate is anothey unusual point. The single specimen 

 is in spirit and runs over and between a number of lorse and 

 attached calcareous fragments, i. e. shells &o. The upright lobes are 

 about 16 millim. long and somewhat flattened. 



