Notices of Memoirs — Prof. 0. C. Marsh. 377 



former of remains of Ichthyosaurus and Plesiosaurus, which, in the 

 latter appear to be entirely wanting ; while the Mosasauroids, a 

 group comparatively rare in the Old World, replace them in the 

 New, being represented by several genera and nmnerous species. 

 Eecent explorations in the Cretaceous deposits of the Atlantic border, 

 and in the region west of the Mississippi, have resulted in the dis- 

 covery of many new forms of this peculiar type of reptilian life. 

 Five forms are described by the author, namely : — 



(1). Mosasaurus prineeps, Marsh, sp. nov., perhaps the largest 

 hitherto found, and when' entire probably represented an animal not 

 less than 75 feet in length. The remains are in excellent preserva- 

 tion, and include the greater portion of the skull with the maxillary 

 teeth ; one quadrate bone, one mandible, and about 26 vertebrge, 

 besides several bones of the extremities. 



(2). Mosasaurus Copeanus, Marsh, sp. nov. represented by portions 

 of a skull, with, some of the maxillary teeth, and part of the cor- 

 responding lower jaws, including the anterior extremity of the left 

 ramus, etc- They indicate one of the smallest Mosasauroids yet 

 discovered, and one very distinct from any hitherto known. These 

 remains. Prof. Marsh considers, may indicate an animal about 25 feet 

 in length. 



(3). Mosasaurus Meirsii, Marsh, sp. nov. Indicated by the crown 

 of a single tooth. 



(4). Baptosaurus (JSalisaurus) platyspondylus, Marsh. Founded 

 on a posterior cervical and an anterior dorsal vertebra; the right 

 splenial bone, and a small portion of the base of the skull, etc. ; 

 indicating an animal about 30 feet in length. 



(5) Halisaurus fraternus, Marsh, sp. nov., established on an an- 

 terior and two posterior dorsal vertebree. The vertebree are more 

 depressed than are those of Macrosaurus Icevis, Owen, or M. validus, 

 Cope, and indicate a smaller animal than either of these species, 

 probably 25 or 30 feet in length. 



Prof. Marsh next describes a new and gigantic fossil serpent 

 {pinophis grandis), from the Tertiary of New Jersey. 



This species is founded upon a single dorsal vertebra, somewhat 

 injured but having the neural arch well preserved. Two other 

 fossil Ophidians have already been described by Prof. Cope, under 

 the genus PalcBophis, namely. P. littoralis and P. halidanus ; these 

 Prof. Marsh suggests should be included in the genus DinopMs, being 

 very distinct from Prof Owen's genus PalcBophis. 



II. Notice of some Fossil Birds, from the Cretaceous and Tertiary 

 Formations of the United States. By Prof. 0. C. Marsh, of Yale 

 College. — The remains of Birds described from European rocks are at 

 present limited in the Mesozoic to the famous Archceopteryx of the 

 Jurassic, and a single species only from the Cretaceous : but in the 

 Tertiary period, and especially in the Miocene and Pliocene, this 

 class was very fully represented by many of the modern types, and 

 numerous species have already been described by European Pal^on- 



