280 ^[r. W. F. c]e Vismes Kane 07i 



may perhaps be accounted for by the difficulties of alimenta- 

 tion, which in some instances would result in the stunted 

 size of adults, whose oro^ans niij^ht be proportionally longer 

 than younger but well-nourished itidlviduals of the same 

 body-iength. The following table will illustrate this. The 

 length of body is measured from the extremity of the head 

 to the base of the third uropod. The figures given are 

 hundredths of an inch. 



The position of the telson relatively to that of the body 

 and third uropod seems to me some index to the sex. In 

 going through a long series I noticed that in normal attitudes 

 with the body fairly extended the telson of the female lies 

 parallel to, and often rests upon the uropod, but in the male 

 it stands more erect and at right angles to the body-segment. 

 The posterior (fifth) pair of pereiopods are proportionally- 

 longer in the female, reaching to the middle, or in large 

 specimens even beyond the extremity of the third uropod, 

 when the body lies straight and the appendage is drawn 

 backwards parallel to it. In the male tiiey scarcely reach 

 the base of the uropod. The brood-plates of the adult 

 female are, of course, when they can be detected, the most 

 certain indication of that sex. One additional observation 

 remains to be added. In dissecting the buccal apparatus I 

 found entangled in the seta of the first maxillary palp a 

 specimen of Chydorus ovalis. Those observers who have 

 examined the contents of the intestinal canal of species of 

 Isiphargus report it to consist chiefly of sandy debris and 

 portions of algte. The presence of an entomostracau in the 

 mouth-organs certainly proves nothing, but the presumption 

 is that these creatures maj feed on animal as well as on 

 vegetable tissues, wdien they are available. My experiments 

 ■with N. siibterraneus and Kochianus substantiate this. 



Niphargus suhterraneusj Leach. 



In the same autumn I made some investigations on the 

 chalk tablelands above Sittingbourne, Kent. Here deep 

 excavations are necessary to tap a spring. The results were 



