1894. NOTES AND COMMENTS. 323 



and complicated folds, in which the spermatozoa lodge until the 

 downward passage of the eggs allows fertilisation to take place. 



Mr. Racovitza has also studied the habits of Sepiola rondeletti 

 and Rossia viacrosoma at the same interesting period of their lives, but 

 the complete account is not yet published. (See Comptes rendus de 

 VAcad. d. sci., cxviii., p. 72.) 



The Habits of a Crab. 



In another part of the paper above referred to, Mr. Racovitza has 

 a note on the habits of Pilnmnus hivtellus. This little crab lives in holes 

 in the rocks at the bottom of the sea off Cape Abeille near Banyuls. 

 In other holes of the same rocks live some small bivalves of the genus 

 Tellina. So long as the molluscs remain quiet, with their shells closed, 

 the crab takes no notice of them. But if one of them moves, then its 

 shell scrapes the rock, and the vibration is communicated to the crab 

 in his hole. After listening for a few seconds the crab sallies forth, 

 and proceeds in the direction of the Tellina ; he then feels for the hole 

 with his claws and, inserting oiie of them, draws out the mollusc, 

 which he carries back to his own den, cracks open, and eats. 



These observations and a few simple experiments show that by 

 means of its otocyst, which is an organ for feeling vibrations rather 

 than for hearing, the crab perceives not only the presence but the 

 whereabouts of the mollusc. This perception is retained in its memory 

 after the vibration has ceased. The actual spot is found not by sight 

 but by touch. The actions of the crab are purely instinctive and show 

 no signs of intelligence ; for any object that is used to scratch the 

 surface of the rock will attract and be seized by the crab, even many 

 times in succession, just as much as if it were a toothsome morsel. 



" The Toilers of the Sea." 

 We have devoted some space to these observations of the 

 Roumanian naturalist, not so much because of their intrinsic impor- 

 tance, though that is not slight, as because they exemplify a side of 

 zoological study that deserves more attention and more encourage- 

 ment than, in this country at all events, it has yet received. It is 

 hardly necessary to point out that there are many structures the true 

 meaning of which will never be apprehended by one who relies on 

 anatomy alone, if indeed they do not escape his observation alto- 

 gether. Everyone admits, in theory, the necessity for close and long- 

 continued study of animals living in their native haunts ; and yet 

 many a zoologist obtains degrees and honours without having seen a 

 single living individual of the animals that he has written about. It 

 is not to be supposed that this state of things exists by the choice of 

 the zoologists. So far as the ornithologists, lepidopterists, and such 

 workers are concerned, the objection cannot, as a rule, be raised. It 

 is the student of marine animals, especially of those that live in 



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