262 



SCIENCE. 



[Vol. XVI. No. 405 



LETTERS TO THE EDITOR. 



*** Correspondents are requested to be as brief as possible. Tlie writer^ s name 

 is in all cases required as proof of good faith. 



The editor will be glad to publish any queries consonant with the character 

 of the journal. 



On request^ twenty copies of the number containing his communication will 

 be furnished free to any correspondent. 



Structure of the Plesiosaurian Skull. 



It is somewhat remarkable, that, in a group of fossil reptiles 

 like the plesiosaurs, the nature and structure of the skull should 

 have remained for so long a time practically unknown. Frag- 

 mentary remains of this very important part of the skeleton are 

 not rare in collections, but none sufficiently complete to make out 

 any thing at all satisfactory of its anatomy have hitherto been 

 described. Very fortunately the museum of the Kansas Univer- 

 sity has recently been enriched by the skull and a large part of 

 the neck of one of these animals, in most remarkably perfect 

 preservation, collected from the Kansas Niobrara cretaceous by 

 Judge E. P. West, assistant in paleontology at the State Univer- 

 sity. Recognizing the value and rarity of the specimen, Mr. 

 West used tbe most scrupulous care in removing and shipping the 

 specimen, and, as now cleaned from its matrix in the museum, it 

 permits most of its structure to be made out with certainty and 

 ease. I have in preparation a full description of the specimen, 

 with illustrations, which will shortly be published in the "Trans- 

 actions of the Kansas Academy of Sciences." Meanwhile, bow- 

 ever, the very great importance of the find renders a brief descrip- 

 tion of its chief characters at the present time very desirable. 



Tbe species I refer provisionally to the genus Cimoliosaurus, 

 though certain characters, as will be seen, do not accord with 

 those given by Lydekker in his recent " Catalogue of Fossil Rep- 

 tilia." Tbe specimen lies upon its side, with twenty-six vertebrae 

 in position; and all, save some of the posterior vertebi-Ee, which 

 were exposed, are in perfect preservation. The cervical vertebrse 

 have the arches and riblets fully co-ossified with no or but very 

 slight traces of their sutural attachments. There is but a single 

 rib attachment, and the zygosphene is rudiuientary. The spines 

 are short; tbe anterior centra, gently cupped; the posterior ones, 

 which increase gradually in slenderness, more deeply so. Tbe 

 parietal bone forms a roof-shaped covering, ascending into a high, 

 thin sagittal crest two or three inches above the brain-case: there 

 is no parietal foramen. There is but oneiempoTal arcade, a broad 

 bar passing directly backward, on a line with the maxilla, to 

 unite with the lower part of the quadrate. The bmits of the 

 quadrate- jugal have not yet been satisfactorily made out. The 

 post-orbital is a slender bone uniting broadly with the jugal be- 

 low, and has no connection with the slender squamosal. There 

 is apparently no post frontal. Lying within tbe comparatively 

 small orbit are eleven or twelve sclerotic plates, touching each 

 other at their edges, and forming the larger part of a ring, a few 

 having been misplaced. The mandibular symphysis is short, and 

 the two sides are so firmly co-ossified that I have found no trace 

 of the suture. There are about twenty teeth in each .iaw, ex- 

 tending far back, the anterior ones very much larger than tbe 

 posterior ones; in the locked jaws the upper ones reaching nearly 

 to the lower margin of the stout mandible. A part of a single 

 bone was found between tbe jaws, which I believe to pertain to a 

 liyoid. 



I need not point out the importance of the foregoing characters. 

 Others scarcely less interesting will be given later. The ones here 

 given, however, are nearly all in conflict with generic, family, 

 ordinal, or even super-ordinal characters hitherto accepted. The 

 sclerotic plates are the first ones described for any of the t^ynap- 

 tosauria, a branch comprising the Chelonia and Sauropterygia. 



The species can be located with neither Polycotylus or Klasmo- 

 saurus, tbe two genera of tbe American cretaceous hitherto de- 

 scribed as having co-ossified neural arches. - I place it, however, 

 under Cimoliosaurus, in Lydekker's acceptation, and shall describe 

 and figure it under the name C. Snoivii, in honor of.Cbancellor 

 F. H. Snow, who has done so much for tbe development of the 

 natural-history department of our university. I append a few 

 measurements: length of skull from occipital condyle to top of 

 pvmMxilla, 18 inches; greatest height of skull to top of parietal 



crest, 9 inches ; length of centrum of second cervical vertebra, If 

 inches; height of centrum of second cervical vertebra, 1| inches; 

 height of spine above centrum, same vertebra, 3i inches; length 

 of centrum of eighteenth cervical vertebra, 3t inches; height of 

 centrum, same vertebra, 2 inches; length of centrum of twenty- 

 fifth cervical vertebra, 8| inches. S. W. Wlliston. 

 University of Kansas, Oct. 2.5. 



On the Characters and Systematic Position of the Large Sea- 

 Lizards, Mosasaurids. 



A NEAKLY complete skeleton of one of the mosasauroid reptiles, 

 collected during the summer in the cretaceous of Kansas, enables 

 me to give full characters of this family, and to determine abso- 

 lutely its relations. 



The skull is nearly, in every respect, of the pattern of the 

 Varanidce ; the premaxillaries co-ossified with nasals, forming a 

 single bone ; frontals single, but indications of former division in 

 front; parietals single ; post-orbital arch complete, — a bony postor- 

 bito-quadrate arch. This arch is formed by tbe postfronto-orbitals, 

 which are free from each other in young specimens, and by the 

 quadratojugal (squamosal); pterygoids and palatines separated, 

 pterygoids with teeth ; vomers separated behind, connected in 

 front; a small ecto-pterygoid (transverse bone); infra-orbital fossa 

 as in Varanidce; nasal opening formed by naso premaxillary, 

 frontal, prefrontal, maxillary; orbits formed by prefrontal, jugal, 

 postfronto-orbital, and a vei-y small portion of the frontal; epi- 

 pterygoid as in Varanidce ; no ossified alisphenoid ; par-occipital 

 (opisthotic) co-ossified with ex-occipital ; petrosal (pro-otic) sutu- 

 rally united or co-ossified with ex- occipital and par-occipital; 

 quadratojugal, squamosal, par-occipital, and quadrate, exactly in 

 the same relations as in Varanidce ; lower jaw as in Varanidce. 



I have to mention here the important fact that the Varanidce 

 and Helodermatidce have, like the Mosasauridce, the peculiar 

 articulation in the middle of each ramus, which enables these 

 animals to extend the lower jaws considerably. Tbe shoulder- 

 girdle is between that of Varanidce and Helodermatidce. There 

 is a very well developed interclavicle, a little divided at the proxi- 

 mal end. The clavicles are small and slender. 



From all this it is evident that the Mosasauridce are very closely 

 related to tbe Varanidce. They simply represent highly special- 

 ized aquatic forms. The enormous size of some of the Mosa- 

 sauridce has to be explained by that fact. .1 may remark here, 

 however, that some fossil Varanidce (Varanus) [Megalonid] pris- 

 cus, Owen, tor instance) from the pleistocene of Queensland reached 

 a length of thirty feet. The Helodermatidce belong to the same 

 group, but the Mosasauridce are very much nearer to the Varan- 

 idce. For this group I retain the old name Platynota. and divide 

 it into two superfamilies, — (a) Varanoidea, 1. Varanidce, 2. 

 Mosasauridce; (&) Helodermatoided, 1. Helodermatidce. 



A full account of the Mosasauridce, with figures, will soon be 

 published. G. Bauk. 



Clark University, Worcester, Mass., Oct. 29. 



Two New Species of Tortoises from the South. 



Through the kindness of Mr. Gustave Kohn of New Orleans, 

 La., I have received for examination a splendid collection of 

 Testudinata from tbe Southern States: Louisiana, Florida, Ala- 

 bama. This collection contains two new species of Malaco- 

 elemmys. 



1. Malacoclemmys oculifera {sp. nov.). — This is one of the most 

 beautiful of the American tortoises, and it is certainly very re- 

 markable that it has not been described before. It was labelled 

 31. Lesueuri, but it is totally different from that. The shell is 

 bjoader and higher. The bony tubercles on tbe vertebral plates 

 are more developed. Each of tbe dermal scutes of the carapace 

 contains a yellow ring, bordered on the inside and outside with 

 dark olive-brown. These rings are especially well developed 

 on tbe costal scutes. This condition induced me to propose the 

 name oculifera. The plastron is yellow, but with markings 

 very much like Chrysemys bellii, Gray. Tbe color of these 

 markings is like the carapace, olive-brown. The head is entirely 

 difilerent from that of any of the described forms of Malaco- 



