52 Gray o?i Sponges. 



when it is broke transversely it appears to be formed irregularly ; 

 and in the Tethya the spiculae are very large, and are felted to- 

 gether, with tlieir points towards the surface, into a hollow sub- 

 globular form, so that it is in fact originally a tubercle, formed of 

 one series of spiculae, which from the intervention of new spiculae 

 between the old ones, increases in diameter, and thus produces 

 the central space. The spiculfe of species which I examined had 

 the base slightly cut into two or three radiating processes. 



Notwithstanding I so strongly urge the placing of this family 

 amongst the Algte, yet I own that I do not know any exactly simi- 

 larly formed vegetable*, although they agree more with them than 

 any known animals ; in fact they appear from their internal struc- 

 ture to approach some of the acicular crystalline substances of the 

 mineral kingdom. 



* Except, perhaps, from the description, Echinella acuta of Linpby, which 

 appears to be similar, and his_^^ure of the granulce, as he calls them, corresponds 

 with the spiculae of several sponges, except that 1 have not observed any trans- 

 verse lines in them, but there has been a difficulty to which kini^dom this genus 

 belongs ; it is now almost generally considered as a vegetable. 



AuT. IV. Description of a new species of Emarginula. 

 By Thomas Bell, Esq. F. L. S. 



Emauginula. Lamarck. 

 Rosea. E. testa ovaia^ cancellaia, epidermide ,fusco induta, in- 

 tus rosea; vertice acuto, valdc recurvo vel subinvo- 

 luto ; marginejisso. 



'This shell is readily distinguished from E. Fissura by the greater 

 curvature of the apex, by being at least as high as it is long, and 

 by the delicate rose colour of the inside in the adult. There is a 

 white line within the shell, running from the fissure to the apex, 

 formed by the gradual obliteration of the fissure, as the shell is in- 

 creased. The animal does not appear to difl"er from that of E. 

 Fissura. 



Found in Poole harbour, where I took three specimens of dif- 

 ferent sizes, last autumn, in dredging. Plate 4, Jig. 1. 



