ISODICTTA. 151 



" On October Stli, 1874, 1 received five specimens 

 of this species from my friend the Rev.. A. M. Norman 

 for examination. They were brought up attached to 

 one of the Atlantic cables by stems of a Hydrozoon 

 which they surrounded in small masses not exceeding 

 half an inch in length and three or four lines in 

 greatest diameter. They were in a good state of 

 preservation, but were very friable. A few minute 

 simple oscula were detected by the aid of a lens of two 

 inches' focus. The dermal membrane affords good 

 specific characters. The disposition of the tension 

 spicula is irregular to a very considerable extent ; their 

 fasciculi sometimes contain eight or ten spicula 

 loosely compacted, at other times they consist of only 

 two or three with single spicula dispersed in various 

 directions around them. They are very equable in 

 size, and are purely acuate in form. The retentive 

 spicula are not very numerous, and are very irregu- 

 larly distributed ; the bidentate equi-anchorate pre- 

 dominate in number ; the tridentate ones are less 

 numerous, and the palmato-tridentate equi-anchorate 

 ones of very rare occurrence. The bihamate retentive 

 spicula are few in number ; they are very minute, and 

 require a power of about 300 linear to render them 

 distinct to the eye. The skeleton is somewhat 

 irregular in its mode of disposition, but small portions 

 of it in parts that have not suffered from compression 

 presented a tolerably regular mode of structure. A 

 very few retentive spicula were observed on some 

 parts of the interstitial membranes, but I did not 

 detect any of the tension spicula on those organs. 



" This species is not referable to any known British 

 one^. but: it is; very probable that we shall hereafter 



