240 . MR. P. LAKE Off THE BRITISH ; [May 1 896, 



Horizon and Locality. — Wenlock Beds : Dudley. 



Affinities. — As already remarked, A. deflexa has usually been mis- 

 taken for A. crenata ; but the resemblance is not very striking, and 

 the differences have already been noted. A. Barrandei, Ang., is 

 very close to A. crenata, and indeed is only distinguished by the 

 presence of a pair of tubercles on each ring of the axis and on each 

 pleura. Several of the British specimens show tubercles upon the 

 axis and pleurae. The presence or absence of these tubercles is 

 probably not a character of specific value, and depends, in part 

 at least, upon whether the actual test of the animal is preserved. - 



The specimens of A. crenata in the Biksmuseum at Stockholm 

 show both forms of tail. LoveVs figure belongs to the narrow-tailed 

 variety. 



Acidaspis qdinquespinosa, Salter MS. (PI. VII. figs. 3 & 4.) 



1846. Odontopleura Brightii, Beyrich, 'Unters. iib. Tril.' p. 20, pi. iii. fig. 6. 

 1854. Acidaspis guinquespinosus, Fletcher & Salter, in Morris's ' Catalogue of 

 Brit. Fossils,' 2nd ed. p. 99 ; 1873. Salter ' Cat. Cambr. & Sil. Foss.' p. 134. 



Body broadly ovate. 



Head short, broad, nearly straight in front ; surface tuberculate. 

 Glabella triangular, occupying at the base about one-third the 

 width of the head ; three pairs of lateral lobes separated one from 

 another by lateral furrows, but not cut off from the median part of 

 the glabella. The facial suture, represented by a raised ridge, runs in 

 a straight line from the anterior margin to the eye and thence in a 

 sigmoid curve to the genal angle. Eyes small, set somewhat behind 

 the middle of the cheeks ; a straight ocular ridge runs from each 

 to the anterior corner of the glabella. Fixed cheeks broad, the 

 portion between the ocular ridge and the glabella tumid. Eree 

 cheeks with a raised margin, which bears a row of short spines ; 

 produced at the genal angle into a short curved spine. Axial part 

 of occipital ring broad, and bearing on its posterior margin five 

 small spines; the posterior margins of the cheeks each bear two 

 spines, exclusive of that at the genal angle. 



The thorax consists of ten segments, and is broader than it is long. 

 Axis very broad, more than one-third the total width. Pleurae 

 horizontal till near the margin, when they are abruptly bent down- 

 ward and then produced into short curved spines; the anterior 

 pleurae are at right angles to the axial line, the posterior pleura? 

 slightly inclined backward, and this is true, in a more marked 

 degree, of the spines. Each pleura bears a prominent tuberculate 

 ridge. 



Tail short, broad, forming a segment of a circle ; it bears one 

 curved ridge on each side, which is produced to form a short 

 primary spine. Outside each primary spine are two secondaries ; 

 and between the primaries are four secondaries. Margin of tail 

 raised. 



Horizon and Locality. — Wenlock Limestone : Dudley. 



It is on the authority of specimens in the Woodwardian 



