618 MOLLUSCA. 



DIVISION. IV.— RADIATA. 



CIa.ss X. Echinodermata—Xl. E>itozoa.—X\l. Acalepfuu—Xlll. Polypi. 



XIV. Infusoria. 

 The arrangement adopted is that of Lamarck, but reversed in the order. 



ORDER I.-HETEROPODA. 



Head distinct, with two eyes, but destitute of arras arranged around the 

 head ; body free, elongated, fitted for swimming horizontally ; no font undnr 

 the abdomen or throat for walking; one or more fins, without any regular 

 order, and not arranged in pairs as in fishes. 



This order consists of three genera, namely; — 1. Phylliroe ; 1. Pterotra- 

 chea ; 3. Carinaria ; of which we have figured, 



Carinaria fragilis. — The Fragile Carinaria. Plate Ixxii. fig 1. Shell 

 excessively thin, hyaline, striated longitudinally, destitute of a dorsal keel. 

 Inhabits the African seas. 



ORDER II.— CEPHALOPODA. 



Head emanating from the bag-shaped mantle, and surmounted by inarticu- 

 lated arms ; provided with suckers, and investing the mnuth ; two sessile 

 eyes ; mouth provided with two horny mandibles ; three he:irts ; the sexes in 

 separate individuals. 



This order contains thirty-three genera. 



1. Sepia. 



2. Loligo vufgaris. — The Common Loligo, or Cuttle Fish. Plate Ixxiii. fig. 

 3. Described, vol. iv. p. 413. 



• 3. Loligapsis Octopus mtlgaris. — The Common Octopus. Plate Ixxiii. 

 fig. 5. The body smooth ; cups widely set and arranged in a double row, 

 and having eight simple elongated arms. Inhabits the European seas. 



4. Octopus. 



5. Argonauta Argo. — Tlie Argus -\rgonauta, or Paper Nautilus. Plate 

 Ixxii. fig. 2. Shell white, involute, extremely fragile, sides with \indulat- 

 cd ridges, and obsolately striate; keel with small tubercles. Inhabits the 

 Mediterranean. 



6. Baculites Faugvsii.—FaMgus,'s Baculites. Plate Ixxii. fig. 3. Erect, 

 cylindrical, opposite sides smooth and depressed ; sutures with lobed denta 

 tluns. 



7. Turrilites costuluta. — The Ribbed Turrilites. Plate Ixxii. fig. +. 

 Erect, turrited ; volutions convex, with transverse ribs, each with a tu- 

 tercle at its base. 



8. Ainmonoceratites glossoidea ^The Glossy Ammonoceratites. Plate 



Ixxii. fig. 5. Large, thick, cylindrical, arcuated, laterally depressed; in. 

 side flatly concave ; apex compressed, tongue-sh;iped. Nineteen inches 

 two lines long. Fossil, East Indies, and in Mount St Catherine, near Rouen. 



9. Orbulites striata.—The Striated Orbulites. Plate Ixxii. fig. 6. Um- 



