324 REPORT — 1872. 



crabs. The specimen is only 8 lines wide and 8 long ; it is remarkably 

 convex in proportion to its size. I have named it after its discoverer Prest- 

 wichia Birtwelli (see Geol. Mag. 1872, vol. ix. p. 440, pi. 10. figs. 9, 10). 



Another new Limuloid crustacean, specimens of which have been obtained 

 from the Dudley Coal-field, and also from Coalbrookdale, has the five thoracic 

 segments free and movable (as in BelUnwus bellidus of Konig), but the 

 pleurse are bluntly acuminate, not finely pointed, as in B. hellulus, and 

 the head-shield is not armed with long and pointed cheek-spines, as in that 

 species. 



I propose to name it BeUimirus Konigianus, after the distinguished author 

 of the ' Icones Fossilium sectiles,' formerly Keeper of the Mineral and Fossil 

 Collections in the British Museum (see Geol. Mag. 1872, vol. ix. p. 439, 

 pi. 10. fig. 8). 



Of foreign Palaeozoic Crustacea, a remarkable new Tribolite (obtained by 

 Dr. W. G. Atherstone, of Gi-aham's Town, Cape Colony), from the Cock's- 

 comb Mountains, South Africa, deserves to be noticed here. It is a new and 

 elegant species of Encrinurus (measuring 3 inches in length), preserved in 

 the centre of a hard concretionary nodule, which has split open, revealing the 

 TrUobite itself in one piece and a profile of it on the other. The profile 

 shows that each of the eleven free body-seg-meuts was armed with a pro- 

 minent dorsal spine nearly half an inch in length, whUst the pygidium was 

 similarly terminated by an even longer spine, slightly recurved at its extre- 

 mity, and all of the spines annulated, as if composed of a large number of 

 joints. Encnnuri with two (and in one case even with three) dorsal spines 

 have been obtained in considerable numbers, both at Dudley and Malvern, 

 and may be seen in Dr. Grindrod's collection, and in the British Museum and 

 many other places ; but a Trilobite with such an array of long dorsal spines as 

 is presented by this African species is very remarkable, and for an Encrinu- 

 rus quite urdque. I have named it after its locality E. crista-galli, which 

 is doubly appropriate (see Quart. Journ. Geol. Soc. vol. xxix. p. 32). 



Among the specimens sent me up by Mr. BirtweU from Lancashire, from 

 the Ironstone of the Coal-measures (so rich in organic remains), was one not 

 referable to the Crustacea. 



On examination it proves to be a new and very remarkable Arachnid, 

 referable to the same genus as one described by Mr. Samuel Scudder, of 

 Boston, U.S., from the Illinois Coal-field, under the name of Architarbus 

 (see Meek and Worthen's Report on the Geology and Palasontology of 

 Illinois). 



I have named it Architarbus subovalis (see Geol. Mag. 1872, vol. ix. 

 p. 385, pi. 9)- . . . 



This is the second British Arachnid I have lately obtained from the Iron- 

 stone of the Coal-measures. 



Tertiary Crustacea. — Some time since I described two new forms of Crabs * 

 from the Lower Eocene, Portsmouth, discovered by Messrs. Meyer and Evans 

 in the excavations for the new Docks there. More recently I have received 

 a fresh series, from which I have been enabled not only to refigure and to 

 fuUy describe the species named by me (on December 21, 1870) Rhachio- 

 soma bispinosa, and to show both the upper and under side of the male and 

 female, but also to record two additional forms, for which I propose the genus 

 Litoricola, naming them respectively L. glabra and L. dentata. These do 

 not belong (like Bhachiosoma) to the Portunidae, but to the Ocypodidae, or 



* Bhachiosoma bispinosa and E. echinata (see Quart. Journ. Geol. Soc. 1871, vol. 

 xxvii. p. 91, pi. 4), 



