UNIVALVE MOLLUSCA. 431 
flattened, covered with angular wrinkles, and dentate on the edge. 
It is of a spotted green outside and of a fine glossy blue within. 
Other very elegant species are Patella umbella (Fig. 212), from 
the African coast; Patella granatina (Fig. 213), the ruby-eyed 
limpet from the Antilles; Patella barbata, the bearded limpet 
Figs. 215 and 216,.—Patella longicosta (Lamarck). 
(Fig. 214); and the long spined Limpet, Paded/a longicosta (Figs. 
215 and 216). 
The fourth family, Cadyptreida, of which the genera Fileopsis and 
Calypftr@a may serve as a type, was classed by the older conchologists 
with Patellide. FPileopsis hungaricus, the Hungarian bonnet shell, is 
rather abundant on some parts of the British coast. 
The fifth family, Fissurediide, contains the 
genera Parmophorus, the duck’s-bill limpet of 
Australia, and Fissure//a, the key-hole limpet, 
which is remarkable for the opening of the 
apex of the shell. 
The sixth family, Hafotide, contains Zan- 
thina, Scissurella, and Haliotis. 
The attention of naturalists has long been Fig. 217, 
< Tanthina communis 
directed to a curious mollusc known under (Lamarck). 
the name of Janthina communis (Fig. 217) ; 
its body is globular, and it presents an opening in front without con- 
tracting itself in order to form the head, which is long and trumpet- 
shaped, terminating in a large buccal opening, furnished with horny 
plates, and covered with little hooks ; and two conical tentacles, 
slightly contracted, but very distinct, each bearing at their external 
base a long peduncle. The foot is short, oval, divided into two 
parts: the anterior, concave and cup-shaped ; the posterior, flat and 
