228 Proceedings of the Royal Physical Society. 



The type specimen has been presented by Mr Thompson to the Eoyal 

 Scottish Museum, Edinburgh. 



The species is a well-marked one, and may be readily distinguished by 

 its symmetrical and dumpy hydrothecee of which the lower third absorbs 

 stain more readily, by the shortness and infra-thecal position of the mesial 

 sarcotheca, with its peculiar bounding septum, and by the presence of very 

 minute denticulations on the margins of sarcothecse and hydrothecee. 



Halicornaria integra (G. O. Sars.). 



As this species has been recorded very seldom, and is described, and 

 that in a general way, only in a journal to which few British workers 

 can have ready access, 1 I give here an account of the salient characters of 

 the species from a well-preserved specimen found in the nets of a 

 trawler at Hull. 



Trophosome. — The colony is 13 cm. high, with a fascicled stem almost 

 2 mm. in diameter at the base, from which several long branches arise. 

 These bear secondary branches, and from these off-shoots of third and even 

 fourth degree arise. The fascicle tubes accompany the cladate tube of 

 branches and off-shoots on their lower portions, but leave considerable distal 

 sections free. The cladate tube lies on the anterior of the fascicle and is 

 divided into long, equal internodes, from the lower half of each of which 

 arises a single hydroclade. 



The hydroclades are alternate, reach a length of 7 mm., and are divided 

 into equal internodes, on each of which occurs a hydrotheca. The cavity 

 of each internode is traversed by from four to eight septa, the number 

 increasing with the age of the internode. The commonest positions of the 

 septal ridges is : one at the base of the supracalycine sarcothecee, one 

 slightly below the intrathecal ridge — one or two lying between these ; one at 

 the base of the hydrotheca, and one below the hydrotheca, almost at the 

 base of the internode. A smaller septum cuts off the mesial sarcotheca, and 

 from it another occasionally runs backwards. 



The hydrothecae are two-thirds the length of a hydroclade internode. 

 They are deep, of almost uniform width, tapering slightly near the bottom, 

 and expanding slightly at the margin. The aperture is circular, and almost 

 at right angles to the hydroclade, and the rim is very faintly crenate, the 

 crenulations being more marked towards the internode. There is a well- 

 developed posterior intrathecal ridge reaching almost half way across the 

 hydrotheca, and recurved at the free margin. 



The supracalycine sarcotheca; are short, reaching just beyond the margin 



1 Forhl Vidensk, Selsk., 1872, Christiana, 1873, p. 100, as Aglaophenia integra. 



