354 MK. A. DENDT ON WEST-INDIAN CHALININE SPONGES. 



Primary and secondary lines may be distinguished, but they are very confused, and 

 there is a strong development of longitudinal fibres. The spicules are for the most 

 part polyserially arranged, and occur scattered outside the fibres as well as in them. 

 The spongin is of a very pale colour, it usually forms a thick sheath completely enve- 

 loping the spicular axis of the fibres. 



The dermal skeleton, like the main skeleton, is a very irregular reticulation, com- 

 posed of spiculo-fibre of extremely variable thickness and with polygonal or rounded 

 meshes varying considerably in size. 



The spicules are long and very slender and somewhat curved ; they are apparently 

 undergoing degeneration. Although commonly diactinal (oxeote or strongylote), yet 

 monactinal forms (styli) seem to be occasionally forthcoming ; but these are perhaps to 

 be regarded as monstrosities, for the nature of the ends varies much. They measure 

 about 0T26 by 0003 millim. 



The species, as I have already indicated, is interesting chiefly owing to the manner 

 in which it demonstrates how cautiously external form must be used as a guide to 

 classification. Yet, although the different specimens, and even the different parts of 

 the same specimen, differ so much in this respect, still there is a close general resem- 

 blance between them all, which, although extremely difficult to express on paper, a 

 careful observer can scarcely fail to detect (vide PI. LX. fig. 2). 



Locality. Nassau, Bahamas. 



Genus Siphonochalina, Schmidt. 

 1868. Siphonochalina, Schmidt, Spongien der Kiiste von Algier, p. 7. 



1881. Tubulodigitus , Carter, Aim. & Mag. Nat. Hist. ser. 5, vol. vii. p. 367. 



1882. Patuloscula, Carter, Ann. & Mag. Nat. Hist. ser. 5, vol. ix. p. 365. 



Diagnosis. — Tubular Chalininse ; tubes smooth, both inside and out, usually narrow, 

 each with a large round opening at the summit. 



For further details with regard to this genus I must again refer to the Report on 

 the Monaxonida collected by H.M.S. ' Challenger,' p. 29. 



Siphonochalina spiculosa, n. sp. (Plate LVIII. figs. 2, 2 a ; Plate LXII. fig. 3.) 

 The single specimen in the collection (PI. LXII. fig. 3) consists of about twenty 

 long, upright, cylindrical tubes, united together at the base, and also occasionally 

 anastomosing at points where they come into contact with one another laterally. 

 Height of entire specimen 27 centim., greatest width 21 centim. The tubes are of 

 nearly the same diameter all the way up, but slightly larger at the top, where they 

 measure about 3 centim., than elsewhere; their walls average about 6 millim. in 

 thickness. The outer surface, though smooth, is rather uneven. The true oscula 

 are very small, and occur scattered over the inner surface of the tubes. The colour 

 of the specimen, in its present condition (dry), is light yellowish grey, and the 

 texture is rather brittle. 



