4 Mr. H. J. Carter on two new Calcispongise. 



chiefly confined to the cloacal surface, pi'ojects into the latter 

 after the manner of the fourth arm of the large quadriradiate ; 

 6, minute, fusiform, acerate, curved, spinous, presenting 

 for the most part the appearance of one end having been 

 broken off and again united, but in the opposite direction to 

 the curve of the spicule generally (/c, and fig. 11, a) ; 7, minute 

 quadriradiate, with one short and three longer arms (Z, and 

 fig. 11, i), chiefly confined, with the two preceding ones, to the 

 surface of the cloacal cavities, where tliey form a more or less 

 dense layer, pierced only by the fourth or internal arm of the 

 great quadriradiate and the openings of the excretory canal- 

 system (fig. 7, a,y, c). These spicules, although they vary 

 somewhat in size, are, on the average, as they are successively 

 described, 100, 36, 62, 58, 10, 4, and 1| ISOOths of an 

 inch in their length and spreading respectively. Size of the 

 specimen (fig. 5) about 9-12ths long, 6-12ths broad, and 

 14-12ths of an inch high. 



Hah, Under surface of the rocks, in company with most of 

 the other siliceous and calcareous sponges here, about low- 

 water mark, in the Laminarian zone. Not uncommon. 

 Loc. Budleigh-Salterton, south coast of Devon. 

 Ohs. I have found sevei-al specimens of this sponge. In 

 some the vents are ciliated, in others unciliated ; that is, 

 crowned with a row of erect linear spicules, or with none at 

 all. Both kinds occur in the specimen from which the illus- 

 tration is taken ; and where the crown is absent or broken off, 

 perhaps from the waves beating upon it twice a day at each 

 falling of the tide, the margin is chiefly bound down by the 

 arms of the great quadriradiate spicule of the surface. 



It differs from Leuconia nivea in the vents being ciliated, 

 in the great spicules of the surface being quadri- instead of 

 triradiate, in the projection of the curved or fourth ray of the 

 great quadriradiate spicule into the cloaca, in the presence of 

 the dark area or point in the centre of the radii of the latter 

 (fig. 12), which at once distinguishes it from Leuconia nivea j 

 where there is no fourth ray to occasion this ; in its lobulated 

 form, where one-third or more of the individual sometimes 

 projecting above the common level of the sponge entails a 

 short cloacal cavity (fig. 7, a) before branching off into the ex- 

 cretory canal-system generally, while in Leuconia nivea the 

 vent, being on the same plane as the rest of the surfiice, which 

 is flat, branches off immediately into this canal-system. 



Thus in Leuconia Johnstonii we have a form midway be- 

 tween Grantia ciliata and Leuconia nivea. 



After having described Leuconia nivea and its large tri- 

 radiate spicules. Dr. Johnston concludes with the following 

 paragraph : — 



