[mat-thew] studies ON CAMBRIAN FAUNAS Si 



6 mm. heads the dorsal suture is close to the glabella in front, as in 

 £. productus i^vom the Wasatch Mountain, and B. HowelU from High- 

 land Range/ and they have a slender spine on the middle of the occipital 

 ring. 



In a head, somewhat older, the shape of the glabella is different. 

 While the three sections of the body have about the same proportions as 

 the adult (head 8 mm., thorax 9 mm., pygidium 5^ mm.,) there is a 

 variation in the glabella toward the adult form ; in this head the glabella 

 has a width of 5 mm. and 3| mm, at the front and back respectively, and 

 a length of 8 mm. There is no spine at this stage on the middle of the 

 occipital ring, but there is one at the back of the ring, this becomes 

 obsolete in the adult. 



Fig. Qa of Plate xxv. in Bulletin 30 has a glabella very like this 

 species ; but Roeminger's species can only be included in Bathyuriscus 

 HoivelU on the supposition that the original figure and description given 

 by Mr. Walcott was incorrect, and that the species had not six seg- 

 ments as therein stated, but seven. As Mr. Walcott absolutely claims 

 Roeminger's species to be this species, I have assumed this claim to be 

 well founded, and have placed it as Walcott indicates. 



This species may be compared with Ayiomocare limbatum of the P. 

 Forchhammeri zone in Sweden,'^ with which species it agrees in a general 

 way ; if we eliminate the flattened borders of the head-shield and 

 pygidium which is an essential character of Anomocare, the resemblance 

 is close ; this genus bears the same relation to Anomocare that Metadox- 

 ides of the Sardinian Cambrian bears to Catadoxides (sub gen. see page 

 93) of the Newfoundland Cambrian ; and B. HowelU is perhaps a later 

 derivation from the stock that produced A. limbatum. 



Bathyuriscus pupa, n. sp. (PI. IT., fig. 5.) 



A dwarf species. Shape without the movable cheeks elongate ellipti- 

 cal. Head-shield three-quarters of the length of the thorax. Glabella 

 nearly three-quarters of the length of the head, somewhat cTub- 

 shaped in front ; four furrows, the posterior turned backward, the 

 second transverse distinct and faint, the third and fourth directed forward, 

 the latter faint. Occipital furrow and ring distinct, the latter wider than 

 the part of the glabella in front of it Fixed cheek narrow, eye-lobe 

 nearly straight. Posterior marginal furrow and fold distinct, but short. 



Thorax of nine segments. Rachis broad and high, nearly half the 

 width of the whole thorax. Pleurae very short, half as wide as long, 

 traversed by a broad triangular furrow, which has a small projecting 

 shoulder near the rachis ; tips of the pleurae turned backward and 

 pointed. 



1 U. S. Geol. Surv., Bull. 30, pi. xxx., figs. 1 and 2a. 



2 Palseont. Scandinav., p. 25, pi. xvilL, fig. 2. 



