NATURAL HISTORY SOCIETY OF GLASGOW. 169 



saxicola, Sclirader, which had been gathered by himself on Rona's 

 Hill, Shetland, in July, 1864. This very distinct species had not' 

 previously been known as a native of the British Islands, although 

 not rare in subalpine regions on the Continent from Switzerland 

 to Lapland, and found also in Greenland. The deeply bifid leaves 

 having the lobes conduplicate, give the plant the appearance of the 

 genus Scapania, a species of which {S. irrigua) was sparingly inter- 

 mixed with the specimens shown. 



Mr John Young made some remarks on four species of Silurian 

 Brachiopoda, new to Ayrshire, which had been found by Mr Eobert 

 Gray — Siphmiotreta miada, Ortliis galea, 0. alata, and Lingula 

 Eamsayii. 



PAPERS READ. 



I. — On New Forms of Crustacea, from the Silurian Bocks at Girvan. 

 By Professor J. Young, M.D., F.G.S. 



Plate I., Figs. 4, 5, 6a, 6&. 

 Among the Crustacea placed in my hands by Mr Robert Gray, 

 more than one form has been added to the previous lists ; and 

 several specimens, whose description follows, are new, specifically, 

 if they have not subgeneric value. 



The parts for determination are the glabella and fixed cheeks. 

 No body rings nor pygidia can be as yet connected with the heads. 

 It is, therefore, probable that the posterior portions of the body 

 have been wrongly referred to other species. This, however, can- 

 not at present be ascertained. The following are the measure- 

 ments of the best preserved specimens, in fortieths of an inch: — 



1. 2 (fig. 4). 3 {fig. 5). 

 Glabella, length, 

 „ breadth. 

 Cheek, length, 

 „ breadth, 

 „ spine, length, 

 Glabella spine, length of fragment, 



probably. 



The glabella is globular, but dips little towards the cervical fold, 

 so that when the animal is placed in its natural position, the median 

 portion corresponding to the basal lobe is nearly horizontal, and 

 the fixed cheeks are in line with the anterior inferior margin of the 



head. 



W 



