PLATH LXXXVI. 299 



Colour. — Olive green or yellow. 



Habitat. — River Exe, Devonshire ; Edward Parfitt, 

 Esq. 



Examined. — In tlie dried state. 



This interesting addition to the list of the British 

 spongillas was discovered in the river Exe at the 

 Salmon Pool near Exeter, by Mr. Edward Parfitt, who 

 found large patches of it rather exceeding an inch in 

 thickness on the timbers of the Wear. On carefully 

 examining it he detected the differences existing be- 

 tween the spicula of its skeleton and those of Spongilla 

 fliiviatiUs, which it very closely resembles in habit and 

 external appearances ; and in his letter to me on the 

 subject he writes, " I am strongly impressed that this 

 is an intermediate form between 8. fluviatilis and 8. 

 Meyeni," and in this opinion I fully concur. Mr. Par- 

 fitt sent a portion of this species to Mr. Carter, who 

 has described it in the ' Ann. and Mag. Nat. Hist.' for 

 April, 1868, as a variety of Sijongilla Meyeni, and 

 designates it 8. Meyeni^ var. Parfitti. How this British 

 spongilla can be a variety of a species that does not 

 exist in England, or to the best of my knowledge 

 nearer than Bombay, is quite past my comprehension, 

 and I have therefore described it as a distinct species 

 under the title of 8. Parfitti. 



The approximation of 8. Parfitti to 8. Meyeni lies in 

 the spination of a portion of the skeleton spicula, but 

 the divergence of the two species is strongly marked in 

 the structural ^peculiarities of the rotulate spicula of 

 their ovaria, not only in the great difference in their 

 respective sizes but more especially in the spination of 

 their shafts. In both species the shafts of the rotulate 

 spicula are frequently spineless. In 8. Parfitti in the 

 fully developed spiculum the shaft frequently has ffom 

 one to three spines, and they always attenuate to an 

 acute point, while in a fully developed rotulate spicu- 

 lum of S. Meyeni the spines are comparatively short 

 and thick, and they terminate bluntly in a figure very 

 like an ace of clubs on a playing card, as represented 



