WAVERLY GROUP SPECIES. 317 



showing an obscure, undefined mesial line ; each of the four angles more 

 or less rounded and strongly furrowed. Surface with distinct, sharply- 

 elevated, finely-crenate transverse costae, that are separated by larger 

 furrows, and all arching a little forward from the angles to an indistinct 

 mesial line, along which their inner ends sometimes terminate alter- 

 nately, or are, in other instances, directly continuous across, without 

 interruption; number of costte in 0.51 inch, where the sides measure 

 0.85 inch across, eleven to twelve, and each bearing about fifteen crenu- 

 lations in 0.18 inch at the same place ; furrows between the costse appar- 

 ently smooth. 



Length apparently from three to four inches. 



This species will be at once distinguished from the last by its very 

 much larger and more distant costse, which apparently also differ in 

 increasing regularly in size, as well as in their distance apart, from the 

 smaller to the larger extremity, instead of continuing of nearly the same 

 size. Cross sections indicate a slightly greater diameter in one direction 

 than at right angles to the same, but this may be due to accidental pres- 

 sure. As far as can be seen in the specimens examined, the rather wide 

 furrows between the costae seem to be smooth, or with only faint traces 

 of minute striae of growth. 



Locality and position : The original type specimens of this species were found in 

 the Waverly group of the Lower Carboniferous. The example from which the fore- 

 going description and our figures were prepared, came from the same horizon at Lou- 

 donville, Ohio. 



CRUSTACEA. 



EJ^TOMOSTRACA. 



Genus CERATIOCARIS, McCoy. 



? Sdbgenus COLPOCARIS, Meek, 1872. 



(Proceed. Acad. Nat. Sci., Philad., XXIV, 333.) 



On first examining the species here placed under the above subgeneric 

 name, their general similarity to certain forms that have been referred 

 to Ceratiocaris of McCoy was readily perceived, but a critical comparison 

 with the figures and descriptions of Prof. McCoy's original typical species 

 of that group, such as his C solenoides, 0. elUpticus, and his more recently 

 described 0. ornatus from the Silurian, satisfied me that our species pre- 

 sent differences of apparently more than specific importance. I there- 

 fore sent some of the specimens to Prof. Dana, of New Haven, with the 



