30 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



fastens 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 

 skin, so that the fish is left a mere hulk of head, skin, and bones. It is 

 especially destructive to fishes taken in gill-nets. In every gill-net set 

 at Monterey in summer, more or less of these empty shells are obtained. 

 When these are taken from the water the hag-fish scrambles out with 

 great alacrity. It is thought by the fishermen that the hags enter the 

 fish after the latter are caught in the gill-net, and that they will devour 

 a fish of lU or 15 pounds weight in a single night. At any rate, large 

 fishes of even 30 pounds are often brought up without flesh and with- 

 out viscera, and we can hardly suppose that they swim about in the sea 

 in this condition before coming into the gill-nets. The fish chiefly eaten 

 are Schastichthys pinniger, miniatus, mystinus, etc., Ophiodon elongatusj 

 FaraUchthys maculosus, and HJiacocMlus toxotes. 

 The hag-fish reaches a length of 14 inches, and is not used as food* 

 The genus PoUstotrema (Gill, MSS.) is distinguished from Heptatrema 

 (Bdellostoma) by the presence of 11 or 12 gill-oijenings instead of 7. 



Family PETEOMYZONTID^. 



3. Ammoccetes plumbeus (Ayres) J. & G. 



San Francisco northward ; seen by us at Seattle and San Francisco. 

 Xothiug especial known of its habits, but it doubtless ascends most of 

 the coast streams in spring. It reaches a length of 8 inches, and is not 

 brought into market except when accidentally mixed with other species. 



4. Entosphenus tridentatus (Ricliardson) Gill. — Lamprey; Lamperina. 



{Petromyzon lividus, ciliaius, tridentatus, and astori Giraixl.) 



Monterey Bay to Puget Sound ; seen by us at Santa Cruz and Asto- 

 ria. It ascends the fresh waters in the spring to spawn, running in the 

 Columbia in June. It reaches a length of more than 2 feet, and becomes 

 very fat. It is never used as food so far as we know. 



Family NOTIDANIDiE. 



5. Notorhynchiis maculatus Ayres. 



From Monterey to Puget Sound. In Humboldt Bay it is extremely 

 abundant, and it is much sought for the oil. 



6. Hexanchus corinus Jordan & Gilbert. — Shovel-nosed Sharl: 



Monterey to Puget Sound; probably not uncommon. A fine exam- 

 ple obtained at Neah Bay (Cape Flattery) by James G. Swan. Another 

 taken by us at Soquel. 



Family HETERODONTID^. 



7. Hetercdontus francisci (Girard) 1)111116^11.— Leopard SharJc ; Bull-head Shark. 



From Point Concepcion southward. Described by Girard from Mon- 

 terey, but not seen by us there, and probably very rarely or never reach- 



