ZOOLOGY AND BOTANY, MICBOSCOPY, ETC. 37 



between the lengths of the two others, and its entire lower edge is 

 toothed like a comb. 



The reason of the large eyes and grasping feet of the one female 

 appears to lie in the requirements of its search after and firm grasp 

 of its prey, acts which are devoted to sexual purposes in the similarly 

 organized males. The question whether the European species of the 

 genus exhibit a similar dimorphism in the females is an interesting 

 one ; in any case, however, their ancestors must have had but one 

 form of mouth. Another instance of difference of alimentation 

 between the male and female is offered by several bees (e. g. species 

 of Euglossa, Melissoda, Xylocojpa), the two sexes of which appear to 

 frequent different plants. 



Dorsal Blood-vessel of some Ephemerid Larvae.*— Herr 0. Zim- 

 mermann directs attention to the special arrangement by means of 

 which the blood from the median dorsal vessel of such a larval form as 

 that of Cloe diptera is enabled to pass, not forwards, but backwards into 

 the caudal setae ; the forward movement of the blood in the contractile 

 tube is, as he shows, effected by the presence of a series of valves 

 which prevent the blood from passing backwards ; in the terminal 

 segment, however, the valve is turned not forwards but backwards, 

 and so it happens that when the last chamber contracts, the blood has 

 to pass into the caudal appendages. From these caudal vessels the 

 blood passes through an elongate-oval orifice into the cavity which 

 surrounds the vessel, and from this it is slowly driven forwards. 



The physiological purpose of this arrangement would appear to be 

 of a respiratory character, an exchange of gases being easily effected 

 through the integument of the setae. The author also notes the 

 presence of another peculiarity : the development, on the surface of 

 the mesothoracic portion of the vessel, of a stalked vesicle, which is 

 directed backwards and contracts irregularly. 



^. Myriapoda. 

 Essays on Myriapods. — The first part of the new (47th) volume of 

 the ' Archiv fiir Katurgeschichte ' is almost wholly devoted to the 

 Myriapoda. Dr. E. Kolrausch f issues a complete revision of the 

 Scolopendridfe, with two plates. Save where lack of material compels 

 him to accept a few of the groups of others, his 15 genera and 103 

 species are based on new and careful estimates of the systematic value 

 of external characters. Dr. F. Karsch \ analyzes the curious genera 

 Sphcerotherium and SpJiceropoeus ; and in a second paper he describes 

 several unnoticed species of Polydesmus and directs particular atten- 

 tion to the male genital appendages. A specimen of P. {Euryurus) 

 tcBuia, in the Berlin Museum, shows on one side a well-formed organ 

 of copulation, paired with an unmodified limb on the other. Dr. 

 Karsch thinks we may have here an example of a " morpho-herm- 

 aphroditic " Myriapod. Each of these two papers has a crowded plate, 

 representing the external genitalia of numerous species. In a third 



* Zeitschr. wiss. Zool., xxxiv. (1880) pp. 404-6 (4 figs.). 

 t Arch. f. Naturgesch., xlvii. (1880) pp. 50-132 (2 pis.). 

 X Ibid., pp. 19-35 (1 pi.) ; 36-49 (1 pi.). 



