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 10 or 15 pounds weight in a single night. At any rate, large 

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

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

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

 are Sehastichthys pinniger, 7niniatus, mystinus, etc., OpModon elongatuS} 

 ParaUchthys maculostis, and RhacocMlus toxotes. 



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

 The geuus Polistotrema (Gill, MSS.) is distinguished from Heptairema 

 [Bdellostoma) by the presence of 11 or 12 gill-openings instead of 7. 



Family PETEOMYZONTID^. f 



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



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

 Nothing 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 (Ricliardsou) Gill. — Lamprey; Lamperina. 



{rctromijzon llvidus, ciUatus, iridentatus, and astori Girard.) 



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 NOTIDANID^. 



5. Notorhynchus maculatus Ayres. ^ 

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



abundant, and it is much sought for the oil. 



6. Hexanclius corinus Jordan & Gilbert. — Shovel-nosed Shark. * 

 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 HETERODONTIDiE. 



7. Heterodontus francisci (Girard) DumMl. — Leopard Sharlc; 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- 



