6 Bulletin 47, United States National Museum. 



habits similar to those of Myxine glutinosa. They fasten themselves on 

 the gills or eyes or isthmus of large fishes, whence they work their way 

 verjM-apidly into the inside of tlie body. They there devour all the flesh 

 without breaking the skin, so that the fish is left a mere hulk of head, 

 skin, and l)ones. (Myxinida-, genus BdeJIontoma, Giiuther, Cat., vili, 511. 

 The generic name nvptatrema, Dumeril, has priority over BdeUostoma.) 



a. Gill opoiiiiiKS 10 to 12 on each side; base of toiigue opiiOBito sixth or seventh iiair of gills. 



POLISTOTREMA, 3. 



3. POLISTOTREMA, Gill. 



Polittotrema, Gll.1, Proc. U. S. Nat. Mus., 1880, 30, (domhey).* 



This genus is distinguished from Heptatrema (BdeUostoma) by the pres- 

 ence of 10 to 14 gill openings, instead of 6 or 7, as in Heptatrema. Two 

 or 3 species known, from the eastern Pacific. (A superlative of itoUq, 

 many ; rpf/ua aperture.) 



6. P0LIST0TRE5IA STOl'Tl, (Lockington). 



(California Hagfish; Lamperina.) 



Gills usuallyt 12 on each side, the number varying from 10 to 14. Teeth 

 10 in each series. Branchial artery dividing opposite sixth or seventh 

 pair of gills. Snout 20 times in total length ; head to first gill opening 

 4i; branchial region 8, tail 8. Plum color, paler below, the edge of the 

 lower fold pale. Skin thin, very lax, and separable from the muscles, 

 excessively slimy. L. 14 inches. Coast of California, and north to Cape 

 Flattery, very abundant about Monterey, burrowing t into theflesh of the 

 larger flounders and Sehastodes. (Named for Dr. A. B. Stout,*of San Fran- 

 cisco.) 



Bitelloiiloma slouH. Lockinoton, Amer. Nat., 187», 793, Eel River, California. 

 BdeUostoma dombey, Jordan & Gilbert, Synopsis, 57, 1883, not of Cuvier. 



* Polistotrema domhey (Cuvier) is a species distinct from P. stouti. It is thus characterized hy Put- 

 nam (Proc. Bost. Soc. Nat. Hist., 1873, 160), from specimens from Chile: " Head about J{, of total 

 length, and contained aboiitl^/^ times in the length of the abdomen. Tail 7 to 8 times in total 

 length. IJase of tongue between the 7tb or 8th pair of gilKs. Gills, 10 on each side. Length 

 from 13 to 22 inches. Coast of Chile." According to Putnam the branchial artery divides at its 

 base into a right and a left trunk in this species. 



Le Owitrohrmiche diimliey, Lacepkdf., Hist. Nat. Poiss., I, 5.31, 1798, Chile, non-binomial. 

 (Inntrobranchnu domhey, Cuvif-R, llegnc Animal, 121, 1817, after Lacepede. 

 lidellonloma 'polylrema, Girarp, Proc. Acad. Nat. Sci. Pbila., 1854, 199, Valparaiso. 

 lideUonloma jyolylrema, GUnther, Cat., vili, 512, 1870. 



f According to Dr. Gilbert, in 54 specimens of Polistolrema sloiiti, 41 were found to have 12 gill 

 opening,- on each side, 12 ha<l 11 on each side, and 1 had 13. Occasional specimens may have 

 either 10 or 14, but the normal number is 12. 



JTheliagtish f.istens itself usually on the gills or isthmus of large fishes, sometimes on the 

 eyes, whence it works its way very rapidly into the inside of the body. It then devours all the 

 flesh of the body without breaking the bkin, so that the fish is left a living hulk of bead, skin, 

 and liones. It is especially destructive to fishes taken in gill nets. In every gill not in summer, 

 at Monterey, more or less of these empty shells of fishes are obtained. When these are taken 

 from the water the hagfish scrambles out with great alacrity. It is thought that the hags 

 enter the fishes after they arc caught. A fish of 10 to 15 pounds weight will he devoured by 

 them in a single night. Large fishes of even 30 pounds weight are often brought up without 

 flesh and without viscera, and they certainly do not swim into a gill net in this cunditiou. 



The fishes chiefly infested are Sehastodes pinniger, miniaius, and myslinus, Ophiodun cUmtjalnf, 

 Paralichthys califomictts, and Rhacochilus toxotet. 



