PLATE XXXIII. 



Mesothyra Neptuni. 



See Plate 32. 

 m. 1 View of the tj pe specimen, natural size, showing the dimensions of the caudal plate and spines 



rtronglj striated urf s of the latter and the ridges on the inner margins of the lateral 



spines for the attachment of the sets. 



Hamilton group. Plainfield, Otsego county. 



Mesothyra spumjsa. 

 See Plate 32. 

 «„ 3 Ventral aspect of the caudal plate and cercopods. The latter have been broken at about one- 

 ,,.,!,- their length, but the remaining portions show the faint pustules upon the surface 

 accompanied by eleyated strise near the articular margins. 

 Hamilton group. Pratt's Falls, Onondaga county. 



Mesothyra (Dithyrocaris ?) Veneris. 



Page 193. 

 The right valve of the carapace flattened in the shale, showing the outline, the acute anterior and 

 posterior spines, the position of the eye-node and the faint lateral carina. ^specimen also 



Fig. 3. 



shows a longitudinal furrow just within the dorsal margin, which merges into the margin at a 

 ly opposi 

 milton g 



point directly opposite the eye-node. 



Hamilton group. In the Marcellus shales on Mud Creek, East Bhomfield, Ontario 



Mesothyra Oceani. 



See Plates 32 and 34. 

 FV A A very large, somewhat imperfect left valve, showing the prominent hinge-angle and its upwardly 

 curved apex, the strong lateral carina and the ornamentation of its inner slope, and the con- 

 spicuous eye-node. 



Portage group. Ithaca, Tompkins county. 

 Fig 5 A smaller specimen of the left valve of the carapace, showing the characteristic surface features 

 and the continuation of the thickened margin into the posterior spine which has been broken 



away. 



Portage group. Ithaca, Tompkins county. 

 Pis 6 \ somewhat .-rushed and imperfect specimen of the abdomen and post-abdomen, showing the 

 .. anterior somite and the longer posterior somite with retrally directed strife. The cer- 

 pods show the strong marginal striatums and the coarse, scattered tubercles. 

 Portage group. Ithaca, Tompkins county. 

 Fig. 7. The post-abdomen, with a portion of the posterior somite : showing the sets attached to the inner 

 margins of the cercopods. 

 The drawing fails to represent with sufficient prominence the striatums and tubercles on the 

 cercopods, and the telson, as represented, is considerably too short. 

 Portage group. Ithaca, Tompkins county. 



