Woodward and Etkeridge — On Dithyrocar'is. 109 



at the anterior end, whilst at the posterior border the indentation is 

 twice as deep and nearly twice as broad as that at the anterior end. 

 The following are the measurements of the two half-carapaces : — 



Large half cara- Smaller half cara- 



pace (Fig. 4). pace (big. 5). 



Greatest breadth 25 mm 22 mm. 



Greatest length ... . 62 „ 55 „ 



Length along the dorsalline 40 „ 30 „ 



Breadth of anterior notch 10 „ ... 12 „ 



Depth of anterior notch 7 ,, 10 „ 



Breadth of posterior notch 23 „ ... 20 „ 



Depth of posterior notch .. 15 „ 15 „ 



Although closely resembling B. granulata in outline, the absence 

 of ornamentation has induced us to give to D. glabra a distinctive 

 specific appellation. 



Locality. — Glebe Quarry, East Kilbride, in shale above the 

 Calderwood Cement Stone (L. Limestone Group). Cabinet of Mr. 

 A. Paton, East Kilbride, who has kindly presented the specimen 

 figured to the Collection of the Geological Survey of Scotland. 



We shall probably be able shortly to separate the carapaces of 

 DitJiyrocaris into two groups, which, upon fuller acquaintance, may 

 form two genera, namely : — 



A. Dithyrocaris proper, represented by those forms having the 

 carapace entire in front, or only slightly indented or curved in outline. 



Dithyrocaris tricornis, Scouler. 



Colei, Portlock. 



ovalis, W. and E. 



testudinea, Scouler ] , oa 



ScowZen, M'Coy |(«'^^«P-?)- 



B. Forms having the carapace more or less deeply indented 

 anteriorly and posteriorly, so as to cause it to separate more readily 

 along the mesial line, prohahly indicating forms in which the shield 

 was (during life) bent more acutely down upon the sides of the body 

 than in the forms (A.) above. 



DitJiijrocaris granidata, W. and E. 



glabra, W. and E. ; and probably also 



? tenuistriata, M'Coy, and 



? Belli, H. Woodw. 



6. DiTHTRocARis? STRIATA, W. and E. (PL V. Fig. 6), Mems. 

 Geol. Survey, Expl. Sheet 23, Scotland, p. 100. 



We have had considerable hesitation in referring this fragmentary 

 specimen of phyllopod-remains to Dithyrocaris, but are less inclined to 

 refer it to Ceratiocaris, because the peculiar striations (partly seen on 

 the fossil and partly on the matrix) resemble those of Dithyrocaris. 

 Unfortunately the posterior border is wanting, and the anterior 

 margin is simply rounded in outline. Only half the carapace is 

 preserved. The length of the carapace would have been about 

 30 mm., its breadth is 15 mm. A median lateral line traverses the 

 half-shield, whilst two marginal lines, following the curve of the 

 carapace, indicate the double border so well shown in D. tricornis. 



