PLATE XXXIII. 
Mesothyra Neptuni. 
See , Plate 32. 
1. View of the tyjie specimen, natural size, showing the dimensions of the caudal plate and spines, 
the strongly striated surfaces of the latter and the I'idges on the inner margins of the lateral 
spines for the attachment of the sete. 
Hamilton group. Plainfield, Otsego cotmty. 
Mesothyra spum^ea. 
See Plate 32. ' • 
2. Ventral aspect of the caudal plate and cercopods. The latter have been broken at about one- 
half their length, but the remaining portions show the faint pustules upon the surface 
accompanied by elevated striae near the ai’ticular margins. 
Hamilton group. Pratt’s Falls, Onondaga county. 
Mesothyra (Dithyrocaris ?) Veneris. 
Page 193. 
3. The I'ight valve of the carapace flattened in the shale, showing the outline, the acute anteiior and 
posterior spines, the position of the eye-node and the faint lateral carina. The specimen also 
shows a longitudinal furrow just within the doi’sal margin, which merges into the margin at a 
point directly opposite the eye-node. 
Hamilton gi’oup. In the Marcellus shales on Mud Creek, East Bloomfield, Ontario 
county. 
Mesothyra Oceani. 
See Plates 32 and 34. 
4. A very large, somewhat imperfect left valve, showing the prominent hinge-angle and its uj)wardly 
curved apex, the strong lateral carina and the oi-namentation of its inner slope, and the con¬ 
spicuous eye-node. 
Portage group. Ithaca, Tompkins county. 
5. A smaller specimen of the left valve of the carapace, showing the charactei-istic surface features 
and the continuation of the thickened margin into the posterior spine which has been broken 
away. 
Portage group. Ithaca, Tompkins county. , 
6. A somewhat crushed and imperfect specimen of the abdomen and post-abdomen, showing the 
narrow anterior somite and the longer posterior somite with retrally directed striae. The cer¬ 
copods show the strong marginal striations and the coai-se, scattered tubercles. 
Portage group. Ithaca, Tompkins county. 
7. The post-abdomen, with a portion of the posterior somite ; showing the setae attached to the inner 
margins of the cercopods. 
The drawing fails to represent with sufficient ju-ominence the striations and tubercles on the 
cercopods, and the telson, as represented, is considerably too short. 
Portage group. Ithaca, Tompkins county. 
