
J.-C, MERRIAM — MARINE REPTILES 247 
Remains of the Primates are very rare in the Miocene of Patagonia, 
but they are entirely characteristie and unequivocally demonstrate the 
presence of monkeys of South American type in the Santa-Cruz beds. 
In the Miocene period Patagonia appears rather to have been an 
outpost than the principal area of mammalian evolution in South Ame- 
rica; hence it is that many groups which we might confidently expect 
to find there are not represented in the Santa-Cruz beds. Nevertheless 
the study of this fauna is of the utmost importance for the under- 
standing of the taxonomie and geographical relations of the modern 
Mammalia. 
À new group of marine Reptiles from the Triassic 
of California. 
By J.-C. MERRIAM (Berkeley). 
In the collections of marine Triassic vertebrates at the University of 
California there are a number of specimens representing a heretofore 
unknown form of swimming Reptile. This form has been made the type 
of a new genus and species having the following characters. 
Thalattosaurus Alexandræ, n. gen. n. sp. 
Cranium elongated, with slender snout. External nares separated 
and not far in front of the orbits. Dentigerous portion of the premaxil- 
laries elongated but shorter than the maxillaries. Premaxillaries and ma- 
xillaries sculptured on the external surface. 
Vomers with two rows of flat, button-like teeth. Pterygoids with four 
or more rows of curved, conical teeth. Palatines not known to be denti- 
gerous. Teeth of the premaxillaries and of the anterior end of the dentary 
slender conical. Posterior part of dentary and possibly of maxillaries with 
button-like, flat or only slightly tuberculate teeth. 
Vertebræ amphicælous, neural spines slender. Dorsal ribs single- 
headed. Coracoid reniform, elongated antero-posteriorly. Scapula narrow. 
Humerus short, much expanded distally. Radius and ulna about half the 
length of the humerus; radius with median constriction. Pelvic arch 
robust, inferior elements not plate-like. 
In its fundamental outlines, the skeletal structure in T'halattosaurus 
is strongly suggestive of the Rhynchocephalia, but like many of the so- 
called rhynchocephalian groups it differs so far from the typical forms 
represented by Sphenodon, Homaæosaurus, etc., that it cannot be included 
in the same ordinal division. It is likewise so different from all of the 
other described reptilian families and orders that it must be given an 
