94 THE FISHERIES OF THE ADRIATIC, 



Calappa granulata ; Cancer pagurus (Granzipord) ; Xantho rivolosns (For- 

 fettila) ; Portunus depurator (Gambcro dell' aid), found in small quantities 

 on rocky shores ; P. arcuatus and P. corrugator, both rare, the latter found 

 chiefly on the Dalmatian coast; Grapsus marmoratus {Granzo piatto), some- 

 times found on rocky beds. 



Pinnothcriis vcterum, "the watchman of the Pinnae" [Granzetto dell 

 Ostrcgd), is found in the shells of living bivalves, such as Pinna, Mytilus, 

 Modiola, Ostrea, &c, in which it seeks refuge, living on the small animalcule? 

 contained in the constant stream of water which flows in and out of these 

 mollusks. 



The fancy of our forefathers has attributed the status thus existing 

 between the two species as arising from a friendly alliance based upon 

 mutual benefits rendered, viz., protection and board afforded, on the one hand, 

 by the mollusk, whilst the duties of the " watchman " consist, on the other 

 hand, in giving due warning of the approach of an enemy, such as a star-fish 

 or crab, thus enabling the host to ensure protection by closing its doors 

 on the intruder. And these observations descend from so early a date, that 

 we find the pinna and the crab amongst the early Egyptian hieroglyphs, 

 bearing the interpretation of the duty incumbent on the " pater-familias " of 

 duly providing for his offspring. According to Grube, the crab is also found 

 in the respiratory cavity of Phallusia mamillata. 



Pinnotheres pisitm, a smaller species than the foregoing, lives in Jlfodiola 

 ■shells, sometimes as many as a whole family, consisting of one male, several 

 females, and their offspring, all in one shell. 



These kinds are generally eaten together with the mollusks. 



Species of Porcellana are also found in the shells of mollusks. 



RADIATES. 



The Echinoderms play a very unimportant part as nourishment to man, 

 although some species are consumed, and even regarded as delicacies, in some 

 countries, for instance, in China, where the Sea-Slug, Holothuria edulis, or 

 Trepang, which attains to a length of i 2 inches, forms an important article of 



