MISCELLANEOUS. 79 



(8.) Lepralia trispinosa. — Plate XXV. Fig. 13. — A specimen of 

 this Lepralia was irregularly circular, about four lines in diameter, and of 

 reddish colour. These cells were of a broad oval shape, with a peculiar 

 orifice towards one extremity, the edge of the lip as if projecting over it. 

 Most of the cells have three, and some of them four long spines, guarding 

 the exterior part. 



Probably the reddish colour results from corpuscula or gemmules 

 occupying the cells. 



Plate XXV. Fig. 13, Lepralia trispinosa, portion enlarged. 



(9.) Lepralia squama. — Plate XXV. Figs. 14, 15. — A specimen 

 which invested a living Ascidia rustica, precisely as a large scale, might 

 have been circumscribed by an ellipse extending eight lines by six. Its 

 figure was irregular, and the surface, following the convexity of the ascidia, 

 rose in corresponding form. 



The cells of this product tended to a circular shape, with a large, 

 flattened triangular tooth inclining over each ; and on the opposite margin 

 seemed to be two short stumps. Red and white colour variegated the 



whole. 



The Ascidia having died from previous injury, or from some other 

 cause, admitted of the Lepralia being detached entire, as the skin of the 

 animal softened. Then it separated as a large thin scale. Two or three 

 weeks subsequent to removal, the colour was converted to pure white, and 

 the substance had become very brittle, now exposing the configuration 

 more distinctly. 



Plate XXV. Fig. 14. Lepralia squama. 

 15. Portion enlarged. 



On the whole, my observations on the Lepralia have been far from 

 satisfactory. The object is always microscopic, seldom plain and definite, 

 and commonly impaired, or in decay. 



Many original specimens, and accurate delineations, are still in- 

 dispensable to render the subject explicit. 



