ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 43 



the case of the 4th and 5th pairs of legs, is supplied by the remark- 

 able forward projection of the exopodite of the 1st pair of abdominal 

 legs, which plays in front of the space between the last ambulatory 

 leg and the carapace. 



As in the case of other shrimps in which the male is not provided 

 with offensive weapons, that sex is smaller than the female ; its chelae 

 are adapted only for prehension of mud ; the only appliances by 

 which the female is grasped in copulation are a bent claw on the last 

 maxillipede, and a strong toothed hook on the inner aspect of the 

 tarsi of the 3rd and 4th legs. The S2mia pterygostomiana of the lower 

 edge of the front of the carapace, which has been used as a generic 

 character in Leander, is here present only in the adult female ; it is 

 thus here merely a sexual distinction ; the young females agree, 

 however, with the males in this, and also, owing apparently to their 

 similar proportions, in the number of bristles on the telson. 



These numerous peculiarities in the structure of Atyoida dis- 

 tinguish it from its allies, Palcemon, Hippolyte, &c,, in the same way 

 as not one but several peculiarities usually separate other species and 

 genera, and also families from each other. The connection between 

 the peculiarities in this case lies in the peculiar mode of life, viz. the 

 use of mud as food-material, and the habit of clinging to plants ; 

 which has caused the modification in such an extraordinary manner 

 of the parts concerned in, or affected by these functions. 



Colour-sense in Crustacea.*— C. Mereschkowsky has experimented 

 with the view of determining whether the lower Crustaceans distinguish 

 colours. 



Larvae of the Cirrhipede Balanus and some marine Copepoda, 

 enclosed in a vessel, seemed fully alive to the difference between 

 light of any kind and darkness ; for whereas, in the dark, they were 

 scattered throughout the vessel, they always gathered about a ray of 

 any light coming from a slit. The author considers, however, that it 

 is exclusively the quantity of light, not the quality, that affects them. 

 Using two slits, one to admit white light, the other coloured, he 

 found that they preferred the former — all gathering round it if the 

 coloured light was deep red or violet, and most of them if the colour 

 was bright red, yellow, or green. They always preferred a bright 

 light like yellow to a sombre one like violet. When two rays of 

 equal intensity were admitted they gathered in nearly equal numbers 

 about them, whatever the nature of the colours. There is, then, a 

 great difference in the mode of perception of light, between the lower 

 Crustaceans and man, and even between them and ants. While we 

 see different colours and their different intensities, the Crustaceans see 

 only one colour with different variations of intensity. We perceive 

 colours as colours ; they only perceive them as light. 



Germs of Artemia salina.f — A. Certes has a note on the 

 vitality of the germs of this species and Blepharisma lateritia. He 

 states that having evaporated some water and collected carefully the 

 sediment, he three years afterwards heated the residue with boiled 



* Comptes Rendus, xciii. (1881) pp. 1160-1. t Ibid., pp. 750-2. 



