222 DR. HINDE AND MR. HOLMES OS' SPONGE-REMAINS 



the body, where it terminates ia a slight inflation. Length of 

 spicule -037 mm., greatest tliickness '029. 



In no recent sponge, so far as we are aware, have any flesh- 

 spicules been described which resemble at all closely these 

 peculiar forms. The presence of a simple axial canal indicates 

 that tbey belong to Monactinellid sponges, and as there is a 

 certain correspondence in form to some o£ the sceptrellas of 

 Latrunculia, it seems preferable to place them provisionally 

 under tbis genus. It is highly probable that, like the sceptrellas, 

 they formed a kind of surface-armour on the dermal layer of 

 the sponge, having the spined apices projecting outwards. 



FlesJi-SpicuIes of Thoosa, Hancock. 



TJioosa HancocM, n. sp. — PI. XI. fig. 41. Spicule stout, cylin- 

 drical barrel-shaped, with a whorl of six subspherical tubercles at 

 tbe top and bottom, and a single tubercle supported on a short 

 stem at either end. The tubercles of the body are sessile, their 

 surfaces are covered with minute spines or pustules. An axial 

 canal is shown as a thin rod in the centre of the body or shaft, 

 Leno-th of spicule '022 mm., widtb "OlS mm., thickness of 

 tubercles -OO^S mm. 



PL XI. fig. 42. Spicule of the same character as the preceding, 

 but smaller and less robust. Length of spicule '018 mm., width 

 •013 mm., thickness of tubercles '003 mm. This and the pre- 

 <3edino- form are precisely similar in character to the so-called 

 mulberry flesh-spicules in the tropical boring sponges Thoosa 

 cactoides and T. hulbosa, Hancock (Ann. & Mag. Nat. Hist. vol. iii. 

 1849, pp. 330, 846, pi. xii. fig. 10«), and also to those of T. socialis, 

 Carter (Ann. & Mag. Nat. Hist. s. 5, vol. vi. 1880, p. 56, pi. v. 

 fiw. 23«). from tbe Gulf of Manaar, but they are smaller gene- 

 rally and the tubercles less developed, whilst the shafts are more 

 robust. The recent spicules form a dense dermal layer to the 

 sponges and appear to be the only spicules present, though in 

 T. socialis Mr. Carter describes some minute circular discs as 

 well. As the fossils represent a distinct species, it may be 

 named Thoosa Hancocki. 



PI. XI. fig. 43. Spicule with short barrel-shaped shaft and 

 two whorls of tuberchs, four apparently in each ; the tubercles 

 are supported on short stalks, similar to those of the terminal 

 tubercles at either end. Length of spicule '024 mm., width 



