294 



Dr. John T. Plummer on the 



with it, it is probably not common, and perhaps is new. The 

 Aulacera, as I have provisionally named this fossil, is a long, 

 somewhat cylindrical body, coarsely and unequally fluted 

 throughout its whole length, and having a tubular cavity pass- 

 ing through it longitudinally. The specimen in my possession, 

 though evidently imperfect, is about three feet in length, and 

 tapers gently to one end, which is almost entire. The larger ex- 

 tremity presents a fractured surface of an oval form, two and 

 three quarter inches by two inches in diameter. Being broken 

 into several pieces, the fossil exhibits the large siphunculoid cav- 

 ity, either filled or lined with calcareous spar, and a light colored 

 interior, while the whole surface of the specimen is of a darkish 

 brown and resembles an extremely thin cuticle. I have repeat- 

 edly, but in vain, sought for a multilocular structure in this prob- 

 able nondescript ; not the slightest indication can be detected of 

 any kind of structure, besides what I have already mentioned, 

 unless I may add two sharp lines which run along opposite sides 

 of the fossil, as if they were the sutures of a long pod. The 

 sketch on the preceding page will give you a tolerable idea of 

 its appearance. It was found in the " marlite." 



Crustaceans. — I have often found fragments of trilobites in 

 this formation, and they have generally been portions of gigantic 



Fig. 9. 



species. Among the largest pieces is one which belonged to 

 an Isotelus megistos, nearly equal in size, it is believed, to Dr. 

 Locke's mammoth specimen. (See this Journ., Yol. xlii, p. 366.) 



