ON THE FOSSIL THYLLOrODA OF THE PALEOZOIC EOCKS. 81 



1. Sp. Emersonii] Clarke, 1882. Op. cit. p. 477, pi. 0. fig. 1. 



This is elliptical-oblong, or elegantly oblong with rounded ends, one 

 of which is parted by a narrow cleft. Length 42 mm. ; width 27 mm. by 

 the figures. 



1a. Sp. Emersonii ('?), he. cit. f. 2. 



This is referred to as being a young form of the foregoing, but it i3 

 obovate l (not oblong), and may be specifically distinct. Length. 12 mm. ; 

 width 8 mm. 



Id. Sp. Emersonii (?), loc. cit. f. 3. 



This shows an elliptico-triangular shape, which may be due to im- 

 bedment in the matrix, and resembles a lateral portion of an Aptychopsis, 

 but it is regarded by Mr. Clarke as a folded Spathiocaris. 



(If belonging to the former, the shield, when complete, would have 

 been about 40 mm. long and 40 mm. where widest; in shape obovate, 

 with narrow, pointed posterior; and with a relatively shallow nuchal 

 suture, sloping at 20°, and cutting off a broad cephalic portion.) 



Mr. Clarke has found many examples of Spathiocaris folded laterally 

 (see 'Amer. Journ. Sci.' ser. 3, vol. xxv. p. 124). 



Spathiocaris Emersonii, as described in the 'Amer. Journ. Sci.' for 

 June 1882, has been found by Mr. Clarke abundantly in some of the 

 Devonian strata of New York State. In 1882 he had already obtained 

 thirty specimens from a layer only a few inches thick ; they varied much 

 in size, from a length of 4 mm. to GO mm. ; aud a fragment of a large 

 individual, probably 80 or 90 mm. long, was met with. 



They occurred in these beds : — 



Chemung Group. — Chemung proper, Naples, Ontario co. ; Lower 

 Chemung Sandstone, Canadice, Ontario co. 



Portage Group.— Upper Portage Sandstone, Wyoming co., Portage- 

 ville ; Upper Black Band, Naples, Ontario co., and elsewhere ; Lower 

 Black Band, Bristol, Ontario co. 



In the lower muddy shales the associates are the common fossils of the 

 Portage rocks, including Goniatites complanatus, H. &c. In the bituminous 

 shales of the ' Upper Black Band,' they occur with fish-remains (Palceo- 

 niscus, &c), conodonts, annelidan teeth, plant-remains, and sporangia of 

 cryptogams ; in the Chemung, in the lowest horizon, with Leiorhynchus 

 mesacostalis, Hall : and in the upper only with Crustaceans allied to 

 Spathiocaris, namely, Bipterocaris (op. cit. p. 121, &c.) 



2. Spathiocaris ungulina, J. M. Clarke, 1884. ' Neues Jahrb. fur Min.' 



&c, 1884, vol. i. p. 182, pi. 4, f. 4. 

 An oval shield ; length (complete), judging by the figures, would be 

 about 34 mm. ; width 26 mm. Cephalic notch narrow and deep, reaching 

 nearly to the centre ; slope about 75°. Rare, Upper Devonian, from 

 Bicken, near Herborn. Very closely allied to Biscinocaris. 



Spathiocaris. 



r Upper Devonian, New York State. 

 Spathiocaris Emersonii A Wit T h T out Goniatites in the Chemung and 



' 1 Upper Portage Groups. 



It- 



_With Goniatites in the Lower Portage Group. 

 ungulina, (in Goniatite bed) Upper Devonian, Nassau. 



If looked at, according to our plan, with the anterior end upwards. 



1884. _ 



it 



