CHARACTERISTIC DEEP-SEA TYPES. — SEA-URCHINS. 101 
Perhaps the most interesting group of sea-urchins discovered 
by the late deep-sea explorations are the Pourtalesie. The first 
Pourtalesia was dredged by Pourtalés in the Straits of Florida, 
— a single specimen only (Fig. 373), but sufficiently perfect to 
enable me to make an examination of this extraordinary type, so 
different at first glance from any sea-urchin previously known. 
Fig. 373. 
Pourtalesia miranda. 
The study of that species, Pourtalesia miranda (Fig. 374), 
showed affinities to a singular family of urchins described from 
the chalk, as well as extended relationship to types considered as 
long extinct. The Ananchytidz, to which the Pourtalesie are 
allied, are perhaps the most typical cretaceous sea - urchins. 
They all have large coronal plates, recalling the Echini, with a 
disconnected apical system characteristic ob many cainozoie spa- 
tangoids ; they have a sunken anal system, some of them a most 
enla de anal beak, and a very striking pouch, in which the 
mouth is placed. They possess rudimentary fascioles, and their 
Fig. 375. — Urechinus naresiamus. — 1-25, Fig. 376.— Profile of Fig. 875. 
tuberculation allies them to the clypeastroids. Another species 
of the same group, which has a wide geographical distribution, 
is Urechinus naresianus (Figs. 375, 376), which seems to be as 
common in some parts of the Pacific as in the Atlantic. 
