256 A MONOGRAPH OF THE 



be seen 'in situ when immersed in Canada balsam, the 

 sarcode being abundant and of a deep brown amber 

 colour. I have named this species in honour of my friend 

 Mr. Robert Patterson, of Belfast, whose valuable labours 

 for the advancement of zoology are too well known to need 

 any eulogy from me. 



19. Halichondria pulchella, Boiuerbank. 



Sponge. Massive, sessile ; surface uneven, smooth. Os- 

 cula simple, dispersed. Pores inconspicuous. Dermal 

 membrane smooth, abundantly spicnlous ; spicula 

 sub-fusiformi cylindrical, terminations incipiently and 

 very minutely spinous ; dispersed or very loosely fas- 

 ciculated, numerous, Tension spicula cylindrical, 

 very long, and extremely slender, rather numerous. 

 Retentive spicula simple bihamate, small and slender, 

 few in number. Skeleton compact ; rete multispicu- 

 lous, spicula sub-fusiformi acuate, rather stout and 

 short, incipiently spinous. Interstitial membranes 

 rather abundantly spiculous ; tension spicula same as 

 those of the dermal membrane ; retentive spicula 

 simple bihamate, small, and slender, very rare. 



Colour. Nut-brown when dried. 

 Habitat. Guernsey, Rev. A. M. Norman. 

 Examined. In the dried state. 



The specimen has apparently been based on a small 

 fragment of a bivalve shell, and was composed of two 

 specimens united by a very small portion of their surfaces. 

 The largest of the two is somewhat fan-shaped, seven lines 

 in height, an inch in breadth, and about four lines in 

 thickness. The form of the second specimen is very nearly 

 the same as that of the first. The oscula are small, and 

 require the aid of a lens of an inch focus to render them 

 distinctly visible. The dermal membrane and its spicula 

 afford the most prominent of the specific characters ; the 

 sub-fusiformi cylindrical spicula have their terminations 



