CRUSTACEA. 139 



while in Glyphcsa they are very strong and meet on the back 

 from opposite sides at an acute angle, without reaching the pos- 

 terior margin. 



Meyeria magna (M'Coy). 



Sp. Char. Carapace about 2i inches long and 1 inch 3 lines 

 deep at the middle of the side ; three strong tuberculated lon- 

 gitudinal ridges on each side of the cephalic part of the cara- 

 pace ; from about the middle of the deep nuchal furrow a row 

 of small tubercles extends halfway to the posterior margin, 

 and higher up (bordering the intestinal region) a similar row 

 on each side extends from the posterior margin nearly half- 

 way to the nuchal furi'ow ; rest of the carapace covered with 

 minute sharp granules, about four in a space of three lines at 

 the middle of the sides ; rostrum short, pointed j abdomen 

 about 3| inches long, each segment with about four irregular, 

 single, crowded rows of granules disposed longitudinally, the 

 broad intervening spaces nearly smooth ; a few irregular groups 

 of granules on the extremities ; the last segment granulated 

 like the carapace ; tail-flaps broad, rotundato-trigonal, finely 

 fimbriated at the ends, each with a strong mesial ridge ; 

 transverse suture of the outer pair strongly marked, serrated ; 

 legs subcompressed (section oval), smooth, the lower edge 

 with a row of minute denticles directed forwards ; third joint 

 of the first pair nearly 4 lines wide, gradually decreasing to 

 the fifth pair, the third joints of which are about 1 line wide. 



Very abundant in the fine Fuller^s earth of the " Lobster beds '^ 

 of the lower greensand of Atherfield, Isle of Wight ; also in the 

 Speeton clay of Speeton, Yorkshire coast. 



[Col, University of Cambridge.) 



Note. — As the Glyphcearostrata (Phil, sp.) [Astacus rostratus, 

 id., Geol. York) has been referred by Herman von Meyer (Neue 

 Gattungen fos. Krebse) and subsequent authors to the G. Mun- 

 steri, I may mention, that on comparing an authentic cast of that 

 species with the English one, I find the latter fully distinguished, 

 as a species, by the hind part of the thorax being much longer in 

 proportion to the depth, even slightly exceeding in this respect 

 the G. pustulosa (V. Mey.), which it exactly resembles in the 

 character of its branchial furrows and their associated lobes, dif- 

 fering however from it and agreeing with the G. Munsteri in the 

 abrupt notch-like narrowing of the margin in front of the nuchal 

 furrow. 



Ord. Entomostraca. 



(Trib. Pcecilopoda.) 



This group being distinguished from other Entomostraca by 

 having crustaceous, didactyle, ambulatory thoracic feet as well as 



