ON CLAVOPORA HYSTRICIS. 261 



were present or not. Although on the side view the form, 

 as figured hy Grunow, differs from mine, still, in most 

 respects, the form under consideration corresponds with 

 Grunow's description, " Ueber einige neue und ungeniigend 

 bekannte Arten und Gattungen von Diatomaceen,' ' Ver- 

 handl. der K. K. Zool. Bot. Gesel. Wien.,' Band xiii, I860, 

 p. 151, Taf. V, fig. 14. In Grunow's figure the outline 

 sufficiently resembles that of mine, PI. VIII, fig. 12, but 

 the median line is straight ; in mine it is doubly arched. 

 The striae are of uniform length throughout, slightly radiate, 

 not reaching the median line, but forming a tolerably broad 

 longitudinal space in the middle of the valve. In my form 

 the striae run up to the median line, except at the middle, 

 where they form a tolerably large free space round the central 

 nodule. They are parallel, rounded off towards the margin. 



O71 Clavopora HYSTRICIS — a New Polyzoon belonging 

 to the Family Halcyonelle^. By G. Busk, F.R.S., 

 F.R.M.S. With PI. IX. 



The curious form here described was procured during 

 the expedition of the Porcupine in the Mediterranean from 

 deep water off the African coast, and was kindly submitted 

 to me for examination by Dr. Carpenter. 



From the inspection of a single specimen it is, of course, 

 difficult to determine whether or not it represents the mature 

 groAvth of the species, or may not be regarded as a young 

 and growing bud. I am, however, inclined to think that it 

 is full grown, from the circumstance that the substance 

 appears to be completely differentiated into definite polypides 

 and tissues. Amongst the latter the muscular seems to me 

 to present such a remarkable peculiarity that even on that 

 account alone it is worth while to place a brief notice of the 

 animal on record. 



The growth is about one eighth of an inch in height, and 

 in the form of a club, with an expanded subglobular head, 

 and it appears to have been affixed to some foreign base by 

 short radical fibres. The stem or peduncle is constituted of 

 a cellular tissue, not unlike that of plants. In each cell may 

 be observed several fibres crossing it for the most part in a 



