374 THE ZOOLOGIST. 



if near to a steep rocky coast exposed to a heavy sea. Shifting 

 sands and soft mud also are objectionable. These indications 

 are useful, but not absolute, especially as regards mud. This 

 per se would not be injurious to reproduction, if it had not the 

 disadvantage of being too soft and slimy. 



When the presence of these marks indicate a likely ground, a 

 test may be made by laying Oyster-mothers, and, at the spatting 

 season, setting collectors. For test-collecting only, the kind of 

 collectors used is immaterial, but when it is a question of collecting 

 for rearing purposes, the collectors should be adapted to the 

 system in view. Thus, if the Italian method of rearing is to be 

 used, wood fascines are preferable ; for they can be easily worked 

 up into pergolari. But if the French or Dutch plan of bedding 

 is to be employed, then tiles are better, for the Oysters can be 

 more easily detached. Where both methods are to be adopted, 

 both sorts of collectors should be used. Collectors of small 

 shells and Oyster culch, as Signor Allodi points out, present 

 serious difficulties in detaching the young Oysters. As regards 

 the position for setting collectors, it may in general be said that 

 they should not be laid in shallow water, or too near the shore. 

 It is difficult to give figures, but at Spezia the collectors are 

 deposited a full f mile from the shore, and at a depth of 12J yards. 

 At Taranto the closest they are to the shore is f mile, but the 

 usual distance is more, and even as much as 12j miles ; the 

 depth is 12^ yards. Of course, in setting collectors, it is advisable 

 to consider the direction in which the current is likely to carry 

 the spat, and to set them not end on, but broadside to the 

 direction of the current. 



As to the number of collectors to be employed, the more the 

 better. In any case not fewer than 400 to 500 should be used at 

 any one point. Thus if a trial is to be made at two points there 

 should be a thousand collectors, and so on. 



The time for setting the collectors naturally coincides with 

 that of the spatting season. The collectors therefore should all 

 be in readiness at the beginning of the month in which the spat 

 is expected. If it is considered desirable to keep them dry and 

 clean till the spat actually appears, and this is an advantage, then 

 test-collectors should be laid. These should be frequently and 

 carefully observed, for the shedding of the spat takes place almost 

 simultaneously among all the spawners, and unless the collectors 



