A New Family <ind Genus of Longer Silurian Cnistacea. 163 



addition to those given b}' Prof. Meek. More recently, ii niueli larger 

 and more perfect specimen (Plate I., figs. 3 and 4) was found b}- Dr. 

 A. J. Newton, of Richmond, Indiana, which adds several interesting- 

 facts. F'inall}^, the discovery, by the writer, of still another specimen 

 (Plate I., figs. 1, 2, and 3), containing the entire posterior portion of 

 the animal, enables us to clear up man^' of the remaining obscurities. 

 It is now certain that this curious creature was not a Cystidean, but a 

 Crustacean ; and that what Prof. Meek mistook for " plates" are in 

 reality the tergal, pleural and sternal elements of the thoracic somites; 

 and the supposed "column" of his specimens, a few segments of the 

 abdomen, which is entire in the example found b}' the writer. 



From a study of the specimen found by Dr. Newton, we are able to 

 determine the form of the somite in front of the one described by Prof. 

 Meek; and also, owing to its excellent preservation, to correctl}^ un- 

 derstand the parts of others, as well as the articulation of the thorax 

 with the abdomen, and the nature of the somites of the latter; while 

 the specimen discovered by myself exhibits most of these facts, and 

 adds that of having the abdomen complete ujith its ajypendages. 



It is now clear, that the part supposed by Prof. Meek to represent 

 the bod\ of the Cystidean, is the posterior somite of the thorax of a 

 Crustacean, of which the body exhibits its proper division into thorax 

 and abdomen, and that the specimen found by Dr. Newton is probably 

 preserved to the cervical groove, separating the thorax from the ce- 

 phalic segments, the former consisting of the two somites described at 

 length below. No portion of the head, and none of the cephalo-thoracic 

 appendages have been found. 



Enofloura, nov. gen. 



Body divided into two distinct regions, the thorax* and abdomen. 

 Somites of the former consisting of well-defined tergal, epimeral, epi- 

 sternal and sternal elements, separated by distinct sutures. Tergal 

 element of the last and sternal element of the preceding somite, not 

 centrall}' auchylosed. Episternal element very largely developed, and 

 strongly carinate on the median line, which forms the lower, outer 

 angle of the somites. Epiraera largely developed, and forming the 

 lateral portions of the dorsal surface. Abdomen oval in section, dor- 

 sally and latero-centrall}' sub-carinate at the sutural lines; composed 

 of fourteen somites, the terminal five bearing longitudinal median pro- 

 cesses on the center of the sterna, while the sixth bears a large trans- 

 verse process, arising from the epimeral region of either side, and con- 



'•'" At present, it seems best not to use the divisions c-ephalo-thorax and post-abdomen. 



