484 



Memoir Sears Foundation for Marine Research 



pharynx on the inner surface of the branchial sieve, whence they are swallowed. ^^ Thus 

 the gill plates, corresponding in position and arrangement to the much simpler and 

 lower transverse ridges borne on the arches of the Rhinopteridae (p. 465), serve the 

 same purpose as the horny gill rakers of the Basking Shark (Cetorhinus) and the gill 

 sieve of modified dermal denticles of the Whale Shark (Rhincodori). It may not be out 



^r 



A ^' 



Figure 112. Man/a iirostris, same specimen as in Fig. lii. ^^ Lateral views of gill plates (outer ends toward 

 right) from anterior side of arch (above) and from posterior side of arch (below), to show difference in shape, 

 about 1.2 X. B Branchial sieve, magnified to show openings and lobelets with denticles, about 28 X. 



of place for us, like so many before us, to call attention to the fact that it is the largest 

 Sharks and Rays and the largest mammals (Whalebone Whales) that strain their food 

 out of the water, while the bony fishes that do so are among the smaller members of the 

 group. 



It is probable,** both from the smallness of their spiracles and from their method 

 of feeding, that the mobulids take in the water for respiration chiefly through their 

 mouths rather than through their spiracles, as all other batoids appear to do (p. 7). 



63. For additional accounts and illustrations of the gill plates of Mobula, see especially: Panceri and de Sanctis (Sopra. . . 

 Cephaloptera giorna, Naples, 1869: 6, pi. i, figs, i, 2; Atti Accad. Pontan. Napoli, 9, 1869: 341, pi. i, figs, i, 2); 

 Dumeril (Ann. Mag. nat. Hist., [4] 5, 1870: 385, 386); Bertolini (Boll. Soc. Biol, sper., 9, 1934: 1270, fig. i, photo); 

 for gill plates of Mania, not previously described, see p. 482. 



64. No actual observations appear to have been made on the method of respiration of the mobulids. 



