292 Professor Owen on Collecting and Preserving Animals. 



more or less embedded in the sand or mud, from which they may be 

 raked into a landing-net. 



With regard to the marine bivalves, rocks, sub-marine clay banks 

 piles, stones, and indurated sand, should be carefully inspected for 

 Pholades, Lithodomi, and other boring species. If the collector should 

 find any of these perforators in the ruins of an ancient temple, or 

 in the remains of any ancient works of art, or any adhering shells 

 (serpules for instance), attached to the surface of such works, the 

 specimens become doubly interesting, especially in a geological point 

 of view. In such cases, the situation should be accurately noted, as 

 well as the distance of the perlbrations from the surface of the sea, 

 either above or below. 



By digging with a wide-pronged fork in sand-banks at low wator, 

 many bivalves, such as Salens, Cardia, Tellince, &c., will be procured 

 alive ; and if the inhabitants of the coast be accustomed to diving, 

 their services should be pi-ocured for deeper water. Care must be 

 taken not to separate the ligament which binds the hinge. When 

 the animal is dead the shell will gape, and the soft pai'ts may be then 

 I'emoved without injury. Attempts to open bivalves, while the ani- 

 mals are alive, generally terminate in great injury to the shells. 



For deep-sea shells, the dredge is indispensable. Dredging re- 

 quires experience to judge of the length of rope to be used ; if there 

 be too much on a sandy bottom, the dredge will bury itself; if too 

 little, it will not scrape properly ; on rocky bottoms the rope must 

 be kept as short as possible ; in deep water, the dredge can only be 

 made to act effectually by placing a weight on the line, which as a 

 rule, may be about one-third of the weight of the dredge, and placed 

 on the line at about two-thirds of the depth of the water ; the object 

 is to sink the rope, and counteract the tendency it has to float the 

 dredge. The contents of the dredge are best examined by means of 

 sieves, of which three should be used, one over the other, first a riddle, 

 next a wheat sieve, and third an oat sieve ; these may be fastened 

 together, the contents of the dredge being emptied into the riddle, 

 and water being poured upon them, the mud, &c., will be washed off 

 and the contents separated, so as to be very easily examined; by this 

 plan, a hundredfold more will be discovered than can be found by 

 searching in mud or sand in the usual manner. Besides shells, num- 

 bers of crabs, star-fishes, sea-urchins, worms, corals, zoophytes, alga;, 

 &c., are procured by the dredge. — The Admiralti/ Manual of Scien- 

 tific Enquiry, published by the authority of the Lords Commis- 

 sioners of the Admiralty, 1849. 



