214 The True Sharks 
and Pteroplatea altavela, in Europe. They are all very much 
alike, olive, with the brown upper surface pleasingly mottled 
and spotted. 
Sting-rays of various types, T@niura, Urolophus, etc., occur 
as fossils from the Eocene onward. A complete skeleton called 
Xiphotrygon acutidens, distinguished from Dasyatis by its 
sharp teeth, is described by Cope from the Eocene of Twin Creek 
in Wyoming. Vertebre of Urolophus are found in German Eocene. 
Cyclobatis (oligodactylus), allied to Urolophus, with a few long 
pectoral rays greatly produced, extending over the tail and 
forming a rayed wreath-like projection over the snout, is known 
from the Lower Cretaceous. 
Myliobatide. — The eagle-rays, Myliobatide, have the pec- 
toral fins extended to the snout, where they form a sort of rayed 
pad. The teeth are very large, flat, and laid in mosaic. The 
whip-like tail is much like that in the Dasyatide, but the spine 
is usually smaller. The eagle-like appearance is suggested 
by the form of the skull. The eyes are on the side of the head 
with heavy eyebrows above them. The species are destructive 
to clams and oysters, crushing them with their strong flat teeth. 
In Aétobatus the teeth are very large, forming but one row. 
The species Aétobatus narinari is showily colored, brown with 
yellow spots, the body very angular, with long whip-like tail. 
It is found from Brazil to Hawaii and is rather common. 
In Myliobatis the teeth are in several series. The species 
are many, and found in all warm seas. Myliobatis aquila is 
the eagle-ray of Europe, Mylzobatis californicus is the batfish of 
California, and Myliobatis tobijei takes its place in Japan. 
In Rhinoptera the snout is notched and cross-notched in 
front so that it appears as if ending in four lobes at the tip. 
These ‘“‘cow-nosed rays,’”’ or “whipparees,” root up the soft 
bottoms of shallow bays in their search for clams, much as a 
drove of hogs would do it. The common American species 
is Rhinopterus bonasus. Rhinoptera steindachneri lives in the 
Gulf of California. 
Teeth and spines of all these genera are common as fossils 
from the Eocene onwards, as well as many of the extinct genus, 
Ptychodus, with cyclospondylous vertebra. Ptychodus mam- 
milaris, rugosus, and decurrens are characteristic of the Creta- 
