52 



continuous also with the skull itself; and the branchial clefts are covered by an opercular 

 menibrane, so that the opening is single; but in the sharks and raj's, which form by far the 

 largest order, the upper jaw and the suspensorial cartilage are distinct from each other, and are 

 moveable upon the skull, and there are several gill openings. The teeth are usually numerous, 

 whereas in the Chimoeras they are not more than six in number. 



There is no doubt that the sharks and rays are good for food ; they 

 may not be so delicate as a flat-fish or a salmon, but they would fur- 

 nish an acceptable and wholesome addition to our food stock. One 

 species, Raia binoculata, the common skate of our coast, is habitually 

 eaten ; the Chinese eat other species ; the poor people along the sea- 

 coast of England eat dog-fishes ; shark's fins are a delicacy in China. 

 If the prejudice against them could be removed, the consumption 

 of these destructive fishes would aid greatly in reestablishing the 

 balance of life in the waters. What chance have our more prized 

 fishes to perpetuate their race, when, in addition to the numerous 

 enemies they previously had to contend with, man comes with his 

 small-meshed nets, kills twenty young for every adult he needs for 

 food; and in addition to this, artificially keeps up a colony of sea- 

 lions at the entrance of the bay, wdiile he neglects to take or kill the 

 destructive sharks and rays, or to thin the schools of porpoises that 

 revel in fish slaughter. Not that it would be advisable to destroy the 

 colony of sea-lions which form one of San Francisco's greatest 

 attractions, but it needs judicious thinning. 



The commonest species of sharks found in the bay and its neigh- 

 borhood are Triads scmifasciatus, the striped or tiger shark, which 

 may readily be known by the dark stripes that descend from the back 

 towards the belly, and which attain a length of more than five feet. 

 Mustelus, Gill, a smaller species of uniform color; Hexancus indi- 

 cus{=Notorhy7ichus maculatus, Ayres,) with seven gill openings instead 

 of the usual five, and very peculiar many-cusped teeth ; and PJiinobatus 

 produdus, Ayers, with very large pectorals, approaching the skates in 

 form, but with the hinder part of the body shark-like. Squatina 

 angelus, the angel-fish or monk-fish, of singular form and forbidding 

 aspect, with a mouth that is terminal instead of underneath the head, 

 and large pectorals, is occasionally taken. 



Of rays, besides the common skate, we have Rhinoptera vespertilio, 

 Ayres, a species with a thick head and an array of flat six-sided teeth, 

 fitted together with all the regularity and closeness of a tesselated 

 pavement. As this form has a wicked-looking serrated spine on its 

 long tail, it is commonly called the sting-ray or stingaree. This is 

 the species which, more than any other of its class, commits depre- 

 dations on the oyster beds so industriously planted along the shores 

 of our bay. A species of torpedo is sometimes met with, but is rare. 

 Of the curious Holocephali, so called because the cartilage of the head 

 is all in one piece, we have Chimosra colliei, Bennett, Hydrolagus col- 

 liei, Gill, a species which is distributed widely along the Pacific coast, 

 and has occasionally been taken near San Francisco. 



Raia binocidata, Girard, Skate — This alone, among the numerous 

 rays and sharks which inhabit the bay, is brought to market regu- 

 larly as an article of food. It is a very near relation of Raia batis, but 

 the spines upon the head differ from those of that species. Many 

 specimens have on each pectoral fin a large sub-circular black ring 

 enclosing a black spot of similar form, but this is by no means con- 

 stant, since though present in some examples eighteen inches or more 

 across the fins, it is often wanting in much smaller specimens. A 



