436 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



la?ozoic countries ; and chapter xix. gives a general resume 

 of our knowledge of Cephalopoda. 



It has been found that the European oyster does not breed 

 in parks made for fattening it, as the water is too fresh for 

 it; but that if artificial tanks are to be self-supporting, tlie 

 water must not be much less salt than on the natural banks 

 from which they are stocked. 



Crustaceans. 



A number of sound-producing Crustacea have been ob- 

 served by Hilgendorf and recorded in Von der Decken's 

 "Reisen in Ost-Africa (Crustacea)," and more recently Mr. 

 "Wood-Mason observed a number of stridulating Crustacea 

 at the Andaman Islands. The sound apparatus consists of 

 two paired organs i.e., organs working independently of eacli 

 other, situated on each side of the body. In certain forms 

 they are seated partly on the carapace and partly on a pair 

 of appendages. Of these some, as in Matuta, have a scraper 

 in the carapace and a rasp on the appendages; while in oth- 

 ers the rasp is placed on the body and the scraper on the 

 appendages, as in Macrophthalmas and allies. In other forms 

 the stridulating organs are situated entirely on the append- 

 ages, as in Ocypode, where the rasp is on one and the scraper 

 on another part of the same appendage. In Platyonyehits 

 bipustulosus the rasps are on one and the scrapers on another 

 pair of appendages. 



Among the curious forms dredged at great depths by the 

 Challenger expedition were certain blind Crustacea, called 

 Willemcesia. The species of this and allied genera have been 

 described by Mr. C. Spence Bate in the Annals and Magazine 

 of Natund History. The eyes in all are rudimentary, the 

 stalk being reduced to a minimum, forming a rigid part of 

 the crust, and covered by the carapace. Now it appears that 

 in the embryo stage the eyes are large and distinctly stalked. 

 A parallel case is seen in the genus Alpheas, the zoea or larva 

 of which has eyes considerably larger and more like the per- 

 manent organ in other genera than the adult parent from 

 which it springs. We may add that the eyes of the young 

 blind craw-fish of Mammoth Cave arc larger proportionately 

 than in the adult. This alteration from the original type to 

 a rudimentary condition is due, Bate rightly claims, to a 



