XXIV INTRODUCTION, 



described and figured by Dr. Mcintosh in the " Linnsean 

 Transactions" for 1862, p. 79. The hairs are not only 

 various in form, but sometimes they will be found con- 

 stant in number. Thus, in the genus Phoxus, we have 

 found the number of hairs on the coxse of the three or 

 four anterior pairs of legs to be constant in the respective 

 species. 



Exuviation and Reproduction of Limbs. 



The power of Crustacea to throw off their skin and 

 replace it by a new one, has long been a recognized fact 

 in all the higher orders. It is, however, on the authority 

 of Mr. Couch, stated by Mr. Bell, in a note to his intro- 

 duction to the " Stalk-eyed Crustacea," p. Ixi., " that the 

 families in which the eyes are sessile in their adult 

 growth .... do not exuviate, or voluntarily throw 

 off their limbs." 



These Crustacea, however, like their higher congeners, 

 renew their integumentary tissues periodically. This is 

 equally true with regard to the alimentary canal, which is 

 cast in connection with the skeleton. The animal shows * 

 no appreciable difference in its habits at the time imme- 

 diately anterior to its throwing off its exuvise. It swims 

 about very actively until the hour of moulting arrives, 

 when it seeks a place of comparative security, where it 

 may remain uninterrupted the necessary length of time 

 for the completion of the process. 



In this position it grasps with the anterior pair of 

 gnathopoda some fixed and conveniently secure material 

 for an anchorage. Here the labour is commenced, and, 

 judging by the quietness and rapidity of the process, 

 appears to be one of no great discomfort. During the 



