162 BRITISH PALAEOZOIC PHYLLOCARIDA. 



wrinkly striee (like those in fig. 1 b, PL XXVII), with obscure, minute interstitial 

 network ; passing into a definite but irregular reticulation with punctate meshes 

 (figs. 3 b — e) ; see the postero-ventral angle of the test, where the head of the 

 right-hand border-spine has been slightly shifted away from its place. 



PI. XXXI, fig. 6. Leeds Mus. Coll., No. 44 b. (A trifid.) 



Size. — Style 15 mm. long; 4 mm. broad at top. Left-hand stylet about 

 30 mm. long ; 5 mm. broad at top. 



Character. — This trifid shows its ventral aspect. The style is shorter than 

 the stylets. The latter appear to have had smooth and strongly grooved surfaces. 

 The style seems to be smooth, with a deep central sulcus, and is probably 

 triangular in section. 



This tail-piece lies close to the front end of the carapace, fig. 3 a, and may 

 have belonged to that individual. 



A similar trifid, specifically the same, most likely, but imperfect, is embedded 

 in specimen No 95 a. 



Plate XXXI, figs. 7 a, b. Leeds Mus. Coll., No. 602. (A caudal plate.) 

 Size. — Length 13 mm. ; width at top 9 mm. ; width at bottom 4 mm. 

 Characters. — This small tongue-shaped plate, tapering downwards to a 

 rounded end, was probably part of the ultimate abdominal segment. It may have 

 been a separate plate coating the outside of the head of the style. The ornament 

 of chevron-lines with the angles downwards is that of the ventral aspect of the 

 abdominal segments (see PI. XXIX, figs. 10 b, 11 a, 12 b, and 13 b). The 

 interstices are irregularly and sparsely punctate. The edges of this little plate 

 being somewhat damaged are ragged all round. 



7*. Dithyrocaeis insignis, sp. nov. Var. multijugata, iiov. Plate XXXI, 



figs. 8 a, b, c, and 9. 



Characters. — Besides a strong mesolateral ridge on each valve, and the usual 

 dorsal ridge, these specimens have another rugose ridge between the mesolateral 

 and dorsal ridges. This ridge is not strange to Dithyrocaris, for it is feebly 

 represented in the very distinct species D. tricomis, PI. XXIV, fig. 1 ; and is 

 traceable in D. Colei, fig. 2. It is a feature also in Chxnocaris tenuistriata, 

 PI. XXI, figs. 8, 9, and 11, stronger than in the foregoing. 



The presence of this juxtadorsal ridge on each side characterises some of the 

 specimens from Eccup as a variety of D. insignis in that locality, inasmuch as 

 the carapace has five instead of three prominent ridges ; and we have named it 



