14G BRITISH PALAEOZOIC PHYLLOCARIDA. 



Dithtrocaris testudinea, Etlieridge, 1S88. Toss. Brit., vol. i, Palseoz.,p. 238. 

 — testudinetjs, W. Hind, 1897. Monogr. Carbonif. Lamell., Pal. 



Soc, pp. 93, 94. 



Specific Characters. — Carapace broad-oval, somewhat convex, and probably 

 clypeiform (Aj)us-\ike) ; anterior notch small and angular ; posterior broad with 

 a sinuous edge (PI. XIX, fig. 7). Posterior spines well developed ; ventral marginal 

 fringe stronger behind than in front. Dorsal junction of the two moieties (valves) 

 simple. Mesolateral ridges strong and rugose. Cephalic and nuchal ridges and 

 protuberances more or less evident. Surface ornamented with wavy and inter- 

 rupted lines sloping obliquely backwards from the dorsal to the ventral region. 

 Abdominal segments marked with similar and chevron-like lines ; of the three 

 caudal spines, the style is shorter than the stylets. 



PL XXIV, fig. 7. Mus. Techn. Coll. Glasgow. 



This specimen was the first-described example of those referred to Dithyrocaris 

 testudinea ; and is therefore here taken first in the account of the species. 



Size. — Length of valve 37 mm.; length of the exposed abdominal segments, 

 free of the valves, and the trifid tail, 20 mm. ; these have been twisted so as to show 

 their ventral aspect; longest caudal spine exposed (one of the stylets), 11 mm. 



The style 10 mm. long. Breadth of the two valves 30 mm. ; incomplete for 

 want of the ventral fringe on each valve ; breadth of one valve about 15 mm. 

 without the fringe. 



Characters. — A broad-oval carapace, slightly convex ; somewhat damaged by 

 pressure, but presenting its chief features (except the marginal fringe) distinctly. 

 It has a triangular notch in front opening into a narrow cleft (caused by pressure) 

 between the antero-dorsal regions of the valves ; also a broad posterior indenta- 

 tion with broken edges. The valves, or lateral moieties of the carapace, are semi- 

 elliptical, and are in apposition by their dorsal edges, but overlapping irregularly in 

 the lower half of the dorsal region, and slightly apart in front. In each valve of 

 this specimeu the ventral border is here destitute of a marginal fringe, such as is 

 usual in other specimens. It is uniformly simple and flattened at the edge. In 

 both valves it ends in a small, obscure spine ; and the posterior border is imperfect 

 on account of fracture. A strong ridge, having the usual rugose structure of 

 overlapping chevron-shaped scales, rises along the middle of each valve, inter- 

 mediate to the margin and the dorsal line. There are also some irregular surface- 

 spots in the cephalic region ; but the cephalic ridge, and the place of the nuchal 

 ridges, are traversed and obscured by local crush-fracture. 



The surface of the valves bears numerous parallel, slightly raised lines, oblique 

 and sinuous ("raised, oblique, recurved, and divaricating," Ethcridge), passing 

 from the dorsal to the ventral border; those reaching its hinder part are there 



