36 FOSSIL MALACOSTRACOUS CRUSTACEA. 



form of this separated piece is also altogether different from the element of which it is the 

 homologne in every other genus. Another remarkable peculiarity is in the form of the 

 epimeral plates, which are remarkably long and narrow. 



The existence of a cardiac region, whicli appears to me to be certainly, altbougii faintly, 

 indicated, in conjunction with a median sulcus by which it is longitudinally divided into 

 two portions, forms, if I am right in this appropriation, an exception to the law laid down 

 in the elaborate and learned disquisition on the elements of the carapace by Prof. Milne 

 Edwards,* that when, as in the case of the common lobster, the carapace is divided along 

 its whole length by a median farrow, it is at the expense of the cardiac region. In the 

 case, also, of Gli/pJio'a, the whole scapular portion of the carapace is thus divided, yet the 

 cardiac region appears to me to be quite as distinct as in any other macrurous form, and 

 more so than in most. 



Phlyctisoma granulatum, viihi. Plate XI, figs. 9, 10. 

 Lobis metabranchialibus granulatis, baud tuberculatis. 



In INIr. Carter's collection are several fragments of a species distinct from the former, 

 which on close examination I find to possess the remarkable peculiarity upon which I have 

 found it necessary to constitute the present genus, namely, the insulation of the mesogastric 

 lobe, of a linear form, by the bifurcation of the median furrow. In the present species 

 the whole of the broad metabranchial lobe is covered with uniform granulations, instead 

 of the distinct tubercles wliich cover this as well as every other part of the carapace in Ph. 

 iuherculatum. The remaining portion of the carapace in this species is also tuberculated, 

 but less thickly than in the former. 



All the fragments which I have seen are too imperfect to allow of any further description, 

 but the generic identity and the specific distinction of the two are equally certain. 



It is found with the former in the upper Greensand of Cambridge. 



* ' Ann. des S. Nat.,' 1851, p. 247. 



