362 ME. A. DENDY ON WEST-INDIAN CHALININE SPONGES. 



croscopical examination it is seen to consist of a finely granular precipitate, mixed, 

 however, with larger particles apparently derived from the breaking-up of various 

 calcareous organisms. This calcareous precipitate is not confined to the surface of the 

 sponge, but occurs also within the horny fibres of the skeleton in the form of very 

 abundant granules. There can be no doubt that it has been deposited from solution 

 in the surrounding water. 



There is also in the collection another variety of the species, not, however, sufficiently 

 distinct to require a varietal name, which possesses a great quantity of a similar 

 finely granular deposit in the skeleton-fibres. Duchassaing and Michelotti further 

 inform us that " un encroutement calcaire tres-mince, facile a detruire, lequel est 

 applique sur un reseau ties-fin forme par les fibres de la surface," exists in their tribe, 

 " Spongise Heterogena?," whatever these may be, comprising the sole genus Cally- 

 spongia. It appears also to exist in Tuba vaginalis, in which " la surface exte- 

 rieure est legerement encroutee effeivescente avec les acides et armee de tubercules 

 aigus, comprimes lateralement et encroutes a leur surface." The presence of a cal- 

 careous deposit is hardly, however, a character which can be considered of any 

 classificatory importance. 



Spwosella sokoria, var. elongata, now (Plate LXIII. fig. 1.) 



This variety is represented in the collection by several fine specimens. It differs 

 from the typical form in having the tubes much elongated and rather narrow ; moreover 

 they are cylindrical and approximately of the same width all the way up. The margin 

 of the tube is usually, though not always, smooth, and the spines on the outer surface 

 are almost entirely obsolete. The venation on the inner surface of the tubes is in most 

 cases not discernible. 



The specimen (PL LXIII. fig. 1) which I have selected as the type of the variety 

 consists of about thirty tubes, most of which present the characters described above, 

 while a few closely approach the typical form and show the spines around the margin 

 and on the outer surface of the tube and the longitudinal venation on the inner surface 

 quite distinctly. The entire specimen is somewhat compressed, as also are the outer 

 specimens of this variety in the collection. This compression may be in part artificial ; 

 but I do not think that it is entirely so. The sponge measures 24 centim. in greatest 

 breadth, and about 30 centim. in height. The diameter of the widest tube is 3 centim. 

 at the mouth, but this is above the average. The tubes are often united laterally for 

 a greater or less portion of their length. 



Almost all the specimens of this variety are infested with very numerous zoanthid 

 polyps, which cause the outer surface of the tubes to appear as though perforated by 

 very abundant small oscula. The polyps themselves, in the dry condition, are of a 

 white colour, and evidently contain a very large amount of calcareous matter, as they 

 effervesce very strongly on the application of hydrochloric acid. They are evidently 



