32 G 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXIIl. 



Hesse, and stated clearly in a footnote at tlie bottom of the page 

 just referred to, can not be the only one. He says in the footnote: 



C'est sans doute a raison de la plus grande epaisscur de leur pcau que je n'ai jamais 

 rencontre ccs parasites sur les Scyllium canicula, catulus et annulatus, qui cependant 

 sont des Squales que Ton trouve plus frequemment que les autres dans notre 

 localite. 



It is very doubtful if the skin of these sharks he mentions is any 

 thicker than that of the dusky shark, Oarcharhinus obscurus, and 

 other large sharks of our own coasts which are commonly infested 



with these parasites. And even if 

 it were thick and tough enough else- 

 where, it would still be thin and 

 soft at the localities mentioned, and 

 easily penetrated by the sharp pro- 

 bosces of these large Pandarids. 

 Some other reason must be found 

 to account for the lack of parasites 

 on the sharks mentioned. 

 Again Hesse writes : "■ 



Fig. 1.— Photograph of dorsal fin of sand 



SHARK, SHOWING DOTH SEXES OF PaNDARUS 

 SINUATUS. In the LOWER BUNCH THE PARA- 

 SITES ARE ENTIRELY COVERED WITH ALG^. 



J'ai, en effet, visite, avec le plus grand 

 soin et depuis un assez grand nombre 

 d'annees, lespoissons de toiltesles espfeces 

 qui frequentent nos cotes et je suis parvenu 

 a trouver vingt Caliges differentes, ainsi 

 que dix Trebles; et toutes, sans aucune 

 exception, ont ete recueillies sur le corps 

 ou sur les brancliies de poissons a peau 

 molle, consequemment autres que les 

 Squales. 



The sharks along ovir Atlantic 

 coast must be very different from 

 those on the coast of France, since the author has found two of the 

 Argulida?, Argulus laticauda and A. 7negaIops, two of the Caliginae, 

 Caligus rapax and Lepeoplitheirus edwardsi, and two of the Eury- 

 phorinse, Alehion gracilis and A. glaher, very commonly upon them. 

 The two last mentioned species are ])ractically confined to the Dog- 

 fish and Sand Shark, and are found all over the outside surface of 

 these fishes, apparently never hunting for any thin places in the skin. 



Furthermore the Caliginse are common also upon Skates and 

 Rays, whose skin is as tough and leathery as that of the sharks,, at 

 least six species being found on these fish. 



We may reasonably conclude, therefore, that the sharks are 

 selected by these parasites as their chosen hosts. And there is no 

 reason for believing that they do not prove as satisfactory as any 

 bony fish (fig. 1). 



" Sain(> article, j). 30. 



