ZOOLOGY. 381 



boli, such as the lumpsucker. The fourth order, Malacopterygii 

 apodes, having no ventral fin, includes the common eel, murena, and 

 electric eel. The fifth order of fishes, Lophobranchi, having tufted 

 gills, includes the sea horse, and pegasus. The sixth order, Pleclo- 

 gnathi, or fish with cheek bones knitted to the jaw, includes the short 

 sunfish, and the file fish. The last great division of fishes, Chon- 

 dropterygii, having cartilaginous fins, includes the Sturiones, or 

 sturgeon and paddle fish ; the Selachii, or shark, angel fish, and 

 saw fish, the sting ray, torpedo, and skate ; and the Suctorii, or 

 lampreys.* 



6. Malacology, including Conchology, treats of the mollusca, 

 most of which are popularly called shell fish, but some of which 

 live on the land, and some are destitute of shells. Conchology is 

 properly the study of the shells ; though sometimes applied to that 

 of the animals themselves. The mollusca, Cuvier's second grand 

 division of animals, have soft bodies, without bones, but mostly 

 protected by shells ; with a double circulation of white blood, in- 

 cluding that from the branchiae back to the heart ; with no spinal 

 marrow, but with nervous ganglia, or bunches, connected by filaments ; 

 having the senses of touch and taste ; while those of seeing, hearing, 

 and smelling are mostly wanting. The nautilus, and cuttle fish, hav- 

 ing a distinct brain, are the most perfectly organized animals of this 

 division ; and they constitute the first class, Cephalopoda, so named 

 from the feet or limbs being attached to the head ; to which class the 

 fossil belemnites and ammonites probably belong. The second class, 

 Pteropoda, with winglike fins attached to the head, includes the clio, 

 and limacina. 



The third class, Gasteropoda, having a fleshy disk, instead of feet, 

 for crawling, includes the Pulmonea, or the slug, snail, and planor- 

 bis ; the Nudibranchiata, as the doris ; the Inferobranchiata, as the 

 phyllidia ; the Tectibranchiata, as the dolabella ; the Pectinibranchiata, 

 or trochus, turbo, melania, nerita, crepidula, conus, cyprea, ovula, 

 voluta, oliva, buccinum, dolium, harpa, murex, fusus, and strombus 

 or conch ; the Tubulibranchiata, as the vermetus ; the Scutibranchiata, 

 as the halyotis ; and the Cyclobranchiata, or patella, and chiton. 

 The fourth class, Jlcephala, having no apparent head, includes the 

 Ostracea, or the oyster, the pecten, sometimes called scallop, the 

 anomia, malleus, pinna, and area ; the Mytilacea, or muscle, and 

 unio ; the Chamacea, as the chama; the Cardiacea, or cardium, 

 donax, tellina, lucina, and venus ; the Inclusa, as the mya or clam, 

 the sdlen or razor shell, the pholas, and teredo, all of which belong 

 to the order Acephala testacea ; while the thalia, ascidia, and botryl- 

 lus, having no shells, form the order Acephala nuda. The fifth class, 

 Brachiopoda, having fleshy arms instead of feet, includes the tere- 



* Agassiz divides fishes into the four following orders : 1. Placoidians, having the 

 skin covered with enamelled plates ; including all the cartilaginous fishes of Cuvier, 

 except the sturgeon : 2. Ganoidians, having angular scales, covered with bright 

 enamel ; among which are the bony pike, and sturgeon : 3. Ctenoidians, having 

 scales with rough or jagged edges ; as the perch ; and 4. Cycloidians, having 

 smooth scales ; as the herring and salmon. 



