PLATE XXXIV. 

 Mesothyra Oceani. 



See Plates 32 and 33. 

 Fie. 1. The carapace of a large individual, the left valve of which is quite imperfect. The rig-lit valve 

 shows the characteristic features of the genus and species. 

 Portage group. Ithaca, Tompkins county. 

 Fig. 2. A light valve of the carapace, proportionally somewhat narrower than that in the preceding figure. 



Portage group. Ithaca, Tompkins county. 

 Fig-. :-;. A specimen retaining the posterior abdominal somite and the post-atxjomen ; showing the true 



proportions and the characteristic ornamentation of these parts. 

 Fig. 4. The ventral aspect of a small post-abdomen, showing the triangular outline of the caudal plate, 

 the characteristic surface ornamentation and the setaceous fimbria- on the eercopods. 

 Portage group. Ithaca, Tompkins cownty. 

 5 A small specimen retaining the abdomen and post-abdomen, enlarged to two diameters The 

 parts of the abdomen are incorrectly represented as one piece, the articular surface of the 

 two somites being at the broken line about one-third the length of the abdomen from the 

 anterior margin. The cancellating striations on the posterior somite are partially due to lateral 

 compression. 



Portage group. Ithaca, Tompkins county. 



