Sponges from the Atlantic Ocean. 215 



yet seen (fig. 14). The bihamate presents the central canal; 

 and the equianchorate differs so much in form between the half- 

 and fully-developed states (fig. 14, c&ai), that, but for such 

 gradations, they would hardly be recognized as belonging to 

 each other. In the half-grown and embryonic form (fig. 14, c ^) 

 the shaft is much less covered in the middle, and the arms much 

 wider than in the matured form, where the shaft is hardly seen 

 from the close approach of the lateral arms to each other ; while 

 all the arms in the matured form appear to be more curved in- 

 wards than in the half-grown specimen, where their expanded 

 state chiefly leads to their appearing to be so much wider. But 

 for there being only one kind of skeleton-spicule, and this in 

 singleness and form being evidently allied to Esjjena, the pre- 

 sence of the anchorate in an equi-ended form would have led me 

 to reject it from the Esperiada3 (Carter), whose most prevalent 

 character is the ^Viequianchorate ; while the villous condition of 

 the dermis, arising from the projecting ends of the skeleton- 

 spicules, equally difi*ers from the beautiful, subhexagonal, or 

 polygonal, structure presented by the surface of Esperia cega- 

 gropila and the like, in which the spicules do not project, but 

 are on a level with the dermal sarcode. The naked, stiff, rigid, 

 coarse, reticulate fibre at the base, composed almost entirely of 

 spicules, is very characteristic of Esperia^ whose parenchyma 

 appears to leave and return to the old spiculo-fibrous structure 

 as required ; or, at all events, the latter when once produced is 

 more durable than the parenchyma, which often, in the newly 

 formed state, returns to and partly overspreads an old skeleton. 

 Hence with the Esperiadse a naked portion of this peculiarly 

 rigid spiculous fibre is as common as it is characteristic. 



Esperia cupressiformis^ n. gen. et sp. PI. XIV. figs. 16-19, 

 and PI. XV. fig. 37. 



General form long, narrow, pyi-amidal, echinated all round 

 with short, linear processes, diminishing in length, becoming 

 thicker as they are inclined upwards towards the summit, 

 and disappearing altogether towards the base, which is some- 

 what inflated (PL XIV. fig. 16). Matured form club-shaped. 

 Processes at first pointed, and afterwards inflated at the ends 

 respectively, becoming more or less united together by a con- 

 tinuous dermal layer of sarcode (fig. 16,^). Free or fixed. 

 Colour whitish grey. (Or, in another form (fig. 19), capitate, 

 head pyriform, compressed (fig. 19, i), supported on a slender 

 stem, terminating in an expanded discoid root at the base 

 (fig. 19, c.) Hispid over the lower half of the compressed head, 

 and also over the root at the base (fig. 19,c). Capitate portion 



