ORDKR PYCXOBRANCHIATA. FAMILY PLAGIOSTOMATA. TRANSVEKSE MOUTHS. 125 



Family STURGEONS ; Sturionida. 



ILLUSTRATIVE EXAMPLES. 

 PLATE 11. 



Genera. SjwHes. f'ommon Name. 



t Sturio ----- Sturgeon. 

 Accipienser- - - { Ruthenu9 .... Sterlet4 



Polyodon - - - Folium. 



( Northern Chimaera, or King 

 \ of the Herrings. 

 f Southern Chimajra, or 

 Fish. 



Monstrosa - 



Chimara - - 



I Southern Chim 

 (Callorhyncha - - -( Elcphant Fis 



CHARACTERS OF THE GENERA. 



1. ACCIPIENSER. Body long, angular, covered with longitudinal rows 

 of bony plates ; snout pointed ; mouth, which is under the muzzle, small, 

 tubular, and toothless ; palatal bones attached to the maxillaries form the 

 jaws ; eyes and nostrils on the side of the head ; no external ear. 



2. PoLYODON. Elongated snout with broad margins ; upper jaw armed 

 with two rows of small teeth, and formed by the union of the palatals and 

 maxillaries, with a pedicle of two articulations. 



3. SPATULARIA. Throat wide and furnished with small teeth ; branchial 

 ap'erture large, covered with a large gill-flap extending nearly to the middle 

 of the body ; skin smooth and scaleless ; dorsal fin single, falciform ; pec- 

 toral small ; ventral opposite the origin of the dorsal ; anal large ; caudal 

 crescentic, its upper lobe longest. 



4. CHIM/ERA. Branchiae opening by a single aperture on either side ; 

 the jaws covered with hard undivided plates instead of teeth ; muzzle 

 prominent and pierced with pores disposed in regular lines ; first dorsal fin 

 above the pectoral, and armed with a strong spine, the second commencing 

 immediately behind the first, and extending to the root of the tail, which 

 is terminated in a thread-like form ; the males distinguished by trifid 

 osseous appendages attached to the ventral fins, on the front of the roots 

 of which are two spiny plates, and a small fringed crest on the head. 



ELEUTHEROBRANCHIATA. DESCRIPTION OF THE SPECIES. 



ACCIPIENSER Sturgeon. The Sturgeons, both in their external form 

 and general internal organization, strikingly resemble the Shark family. 



They are of large size, 

 some having been found 

 to measure from six to 

 eight feet in length, and 



Sturgeon. to we '8 h frora two to 



three hundred pounds. 



The Common Sturgeon (A. Sturio) is about six feet long; its eyes and 

 nostrils are on the side of the head, and barbules issue from the muzzle : 

 there is no "external ear, and the air-bladder is large, communicating with 

 the gullet by an extensive opening. 



Along the northern coasts of Europe, and in some rivers which they 

 ascend, the Common Sturgeon is very abundant, and extensive fisheries are 

 established for its capture. The flesh is generally agreeable, and their eggs 

 and roe are made into caviare, while the finest isinglass is produced from 

 their thick air-bladders. 



The Sterlet (A. Ruthenus) is about two feet long ; its flesh is highly 

 esteemed, and the caviare made from it is reserved for the Russian Court. 



POLYODON (SPATULARIA of Dr. Shaw). The individuals of this genus 

 have a general resemblance to the Sturgeons ; but their gill-openings are 

 wider, and the gill-lid extends to hah the length of the body ; gape much 

 cleft; teeth numerous and small. The spinal cord is like that of the 

 Lamprey, also the spiral valve, which is common to most of the order. 

 They have an air-bladder, but the pancreas is partially divided into caeca. 



There is but a single species known the P. Folium (Plate 11); it is 

 found in the Mississippi, and of its habits little is known. The spatula- 

 like muzzle is about four or five times as long as its breadth, and upon its 

 upper surface has a middle keel-shaped ridge, which is gradually lost about 

 two-thirds from its base, resembling the midrib of a leaf, and the resemblance 



is rendered more close by the reticular ridges observed on each side, and 

 hence Lacepede has given the specific name feuille, leaf; on its under 

 surface the membrane covering it forms a hollow in which the lower jaw is 

 received. 



CHIMERA. Of this genus, which gets its name from its uncouth form, 

 there are but two species : 



The Northern Chimoera (C. Monstrosa), called by the Norwegians " King 

 of the Herrings;" measures about three feet long; is of a silvery colour 

 spotted with brown ; at night its eyes are brilliant like those of the Cat, 

 whence in the Mediterranean it is called the Sea Cat. It is often seen 

 lurking among the shoals of Herrings. The Norwegians salt its roe, and 

 express an oil from the liver, which they employ for certain diseases of the 

 eye ; of the tail they make pipe-pickers ; the flesh is not eatable. 



The Southern Ckimoera (C. Callorhj-ncha), named by Cook the Elephant 

 Fish, is distinguished from the preceding species by a fleshy projection on 

 the muzzle in the form of a hoe, from which it has acquired the name given 

 by Cook. Its general colour is silvery; brownish on the upper parts. 

 Native of the Southern Seas. (Plate 11.) 



ORDER. PYCNOBRANCHIATA, VEL BRANCHIS FIXIS. 



CLOSE GILLS. 



THE gills of this Order are attached to the outer edge, having a separate 

 opening, through which the water from each gill escapes. They form two 

 families. 



Family TRANSVERSE MOUTHS ; Plagiostomata. 

 ILLUSTRATIVE EXAMPLES. 



PLATE 12. 

 Generm. Species. Common Name. 



Squalus - - - - Carcharius - - - Whit* Shark. 



Squatina - - - - Angelus - - - - Angel-fish. 



Torpedo - - - - Narke ----- Spotted Torpedo. 



Raja ----- Clavata - - - - Rough Ray. 



Family LAMPREYS, OR ROUND MOUTHS ; Cyclostomata. 



Petromyzon - - - Marinus ... - Sea Lamprey. 

 Gastrobranchus - Caecus ----- Myxine or Hog. 

 CHARACTERS OF THE GENERA. 



1. SQUALIS. Muzzle prominent; beneath it in front the nostrils, not 

 elongated nor with lobes; teeth cutting, pointed, and often serrated on 

 their edges ; inspiracles sometimes extremely small ; branchial apertures 

 either partially above the pectoral fins or entirely before them ; first dorsal 

 fin much in front of the pectorals, second opposite the anal ; caudal fin 

 with a second lobe beneath, giving it a more or less forked form. 



2. SQUATINA. Mouth at the extremity of the muzzle ; head flat and 

 rounded in front ; eyes on the dorsal surface ; inspiracles ; body broad and 

 flattened horizontally ; pectoral fins large, extending forwards, but separated 

 from the back by a deep cleft, in which are the openings of the gills ; 

 dorsal fins behind the ventral ; no x anal fin ; cauda;' fin having one lobe 

 above and the other below the extremity of the tail 



3. TORPEDO (Lat. torpeo, 1 numb). Teeth small and sharp; body 

 flattened, oval, and slightly notched in front; skin smooth and bare ; tail 

 short, thick, fleshy, and surrounded at its tip with an oblique terminal fin ; 

 dorsal fins two, small, and upon the root of the tail ; pectorals large ; space 

 between the head, gills, and pectoral fins filled on each side with an electric 

 organ, consisting of polygonal columns. 



4. RAJA (Celt. roe). Body of a roundish form, flattened and very wide 

 from the junction of the pectoral fins with the muzzle ; ears and eyes on 

 the upper, and the mouth, nostrils, and gill apertures on the under surface ; 

 teeth small and close set in a tessellated form ; tail slender, furnished with 

 two small dorsal fins, and sometimes with an imperfect caudal fin. 



1. PETROMYZON (Gr. irirpoc, a rock, and pluraia, I suck). Head thinner 

 than the body ; mouth beneath hollowed like a cup, its edge surrounded 

 by a fleshy lip, and its cavity beset with fleshy tubercles covered with very 



