THE 



aEOLO&ICAL MAGAZINE. 



No. C— OCTOBER, 1872. 



I. — Notes on some British Paleozoic Crustacea belonging to 



THE ORDER MeROSTOMATA. 



By Henry Wood^vard, F.G.S., F.Z.S. ; 

 of the British Museum. 



(PLATE X.) 



On the Genus Hemiaspis, H. Woodw,, 1865.^ 



Species 1. — Hemisaspis Umuloides, H. Woodw., PL X., Figs. 1 and 2. 



Wlien I first drew attention to this genus at the Bath Meetino- 

 of the British Association in 1864, only one nearly perfect speci- 

 men was known. Mr. Salter was acquainted with this form, so 

 long ago as 1857, and referred to it, among other new and 

 undescribed Crustacea, in a paper "On some New Palaeozoic 

 Star-fishes" found at Leintwardine, Shropshire,^ under the name of 

 Limuloides. Portions of several others had also been met with, to 

 which Mr. Salter attached MS. names in the Museum of Practical 

 Geology, Jermyn-street, but they have not been heretofore described. 

 The most perfect of these Limuloid forms was described by me in a 

 paper read before the Geological Society in June, 1865.^ (See 

 Plate X. Fig. 1.) 



Since that date other fragments have been found, and also 

 another nearly perfect example (obtained by the late Mr, Henry 

 Wyatt-Bdgell) of the form named by me Hemiaspis limuloides, 

 which, having the upper central portion of the carapace preserved, 

 nearly completes our knowledge of this species. (See PL X. Fig. 2.) 

 The great interest attaching to this form arises from the fact that it 

 offers just the desiderated link by which to connect the Xiphosura 

 with the Eurypterida. Limuli, apparently differing but little as 

 regards their carapace from the recent species now found living on 

 the coasts of China, Japan, and the north-east coast of North America, 

 occur as early as the deposition of the Solenhofen Limestone of 

 Bavaria ; and in the Coal-measures of England and Ireland several 

 species of Bellinuri and Prestiviehioe occur, in which behind the 

 cephalic shield the body is composed of five more or less free 

 thoracic segments, and the rudimentary abdomen, if not anchylosed 

 in all, is so in most. (See Plate X. Figs. 8, 9, and 10.) 



^ Extracted from the Author's Memoir on the Merostomata, Part iv p 174 

 Pal. Soc. Mod., vol. for 1872. 



^ See Anu. and Mag. Nat. Hist., 2nd series, vol. xx., 1857, p. 321, 

 ' See Quart. Journ. Geol. Soc, 1865, vol. xxi., p. 490, pi. xiv., tig. 7. 



"VOL. IX.— NO. c. 28 



