F. R. Cowper Reed — Undescnbed Trilohites. 11 



posterior fork. The pygidium differs in being relatively narrower, 

 in possessing a shorter axis with more rings, in the extremities of 

 the first pleura3 projecting beyond the margin, and in the posterior 

 margin being less deeply excavated. 



Proetus Fletcheri, Salter. (PI. I, Figs. 5 and G.) 



1873. Froetus Fletcheri, Salter: Cat. Camb. Sil. Foss. Woodw. Mas., p. ISi 



(« 825, n 828). 

 1877. Froetus Fletcheri, Salter: Woodward, Cat. Brit. Foss. Crust., p. 56. 

 1891. Froetus Fletcheri, Salter: Woods, Cat. Type Foss. Woodw. Miis., p. 151. 



This species, which is recorded by Salter (loc. cit.) from the 

 Wenlock Limestone of Dudleys is mentioned by him after 

 Pr. latifrons (McCoy) as "a broader species in all parts, more like 

 Pr. Byckholti (Barr.) than Pr. latifrons (McCoy)." 



There are three specimens of Pr. Fletcheri in the Woodwardian 

 Museum, which were labelled by Salter a 825 (2) and a 828, and are 

 thus entered in his "Catalogue." But mounted on the same tablet 

 are seven other unlabelled specimens of Proetus, of which only one 

 belongs to this species, all the others showing points of difference. 

 There are four other specimens of the true Pr. Fletcheri in the 

 Woodwardian Museum, three of which are from the Fletcher 

 Collection and the other from the Leckenby. 



The specimens from which the following description is drawn up 

 are those three labelled by Salter a 825 (2) and a 828. 



Diagnosis. — General shape longitudinally oval, more than twice 

 as long as broad. 



Head-shield broadly parabolic, about twice as wide as long, gently 

 concave posteriorly, moderately convex from side to side, bent down 

 in front. Genal angles produced into spines. 



Glabella very broadly oval, as broad as long, more than one-third 

 the width of the head-shield at base, narrowing slightly towards the 

 obtusely rounded anterior end, which reaches the anterior border of 

 the head-shield ; gently convex from side to side, bent down steeply 

 in front of eyes.^ Surface marked by two pairs of furrows, but 

 anterior pair generally obsolete. Basal pair of furrows short, weak, 

 shallow ; curve slightly backwards ; situated at level of middle of 

 eye and at more than one-third the length of glabella from neck- 

 furrow. Anterior pair of furrows when present very weak, directed 

 obliquely backwards from level of anterior end of eye. 



In Salter's specimen a 825 (here figured PI. I, Fig. 5) there is an 

 additional pair of small pit-like impressions on the glabella, situatetl 

 behind the basal furrows and close to the occipital furrow, and about 

 half-way between the axal furrows and the median line of the glabella. 

 I have not noticed them preserved in the other specimens, but they 

 may be compared with somewhat similarlj' placed basal pits on tlie 

 glabella of some specimens of Pr. boheiuicus (Corda).'- 



1 Owing to this strong downward bend of tlie front end of the glabella, the shape- 

 seems to be subeircnlar in Fig. 5. 



2 Earrande: Svst. Silur. Eohem., vtd. i (18.V2;, p. 452, pi. xvi, figs. G, 7. 



