96 AlS'NUAL REPORT. 



It was conjectured by M. Siebold that these were similar to the seminal tubes 

 discovered by him upon Diaptomus. The act of copulation in Diaptomus, as 

 described by him, is so strange and improbable that it is hard to accept without 

 some hesitation. He says that "the male does not accomplish a true coition but 

 attaches to the female, during copulation, a tube containing spermatic liquor. 

 This tube contains, beside the zoosperms, two substances of which one swells by 

 the influence of water, and chases out the whole contents of the tube. The other 

 substance coagulates, leaving in the middle of the mass a canal by which the 

 zoosperms arrive at the vulva." 



In the case of the Canthrocamptus, however, the appendage is apparently of a 

 different nature, being corneous and harder than the rest of the animal, more- 

 over in no case have more than one of these been observed on the same female. 

 Jurine, howpver, says that this body is never seen till after she has several times 

 laid eggs. Dr. Baird adds that he has never seen more than one on the same 

 female, and that no mature female is met without it, even though the ova are 

 attached. My own observations accord with the above, but I am unable to add 

 any suggestion as to the use of these organs. 



The females are larger and usually darker in color than the male. 

 Habitat. — Shallow lakes and pools; everywhere abundant. 



This si>ecies will repay well patient study, and from its abundance is easily 

 found. This western variety is distinguished from the eastern type by the shape 

 of the head, the greater brevity of the caudal stylets, the shape of the ova sac, 

 the greater size of the fourth joint of the male antennae, and other minor differ- 

 ences, which no great stress is laid upon, however; and these variations may be 

 due to inaccuracies of the drawings of Baird's book. (See plate V.) 



Sub-family 3. Steropince, Dana. 



Characters. — Form somewhat like Sapphirina, but the eyes minute, and gener- 

 ally situated in a prominence in the front. Superior antennae 

 short. Feet of the first pair monodactyl as in Cor^csecidee. Cau- 

 dal stylets short, sub-cylindrical. 

 Genus 1. Zaus, Goodsir. 

 Genus 2. Sterope, Goodsir. 

 No member of the family was met witn. 



FAMILY III. CORYC^ID^:. 



The species are all oceanic. A species of Sapphirina is figured in the Rep. of 

 Fish and Fisheries for 1871 and 1872. 



TRIBE II. DAPHNIOIDEA. Dana. 



Bihliography. — Daphnioidea, Dana, Rep. Wilkes' Expl. Ex., p. 1262. 



Cladocera, Baird, Brit. Entomost p. 62, 1850. 



Burmeister, But. zur Naberg. Der Rankenfass. 



Daphnides, Straus. Mem. Mus. d'Hist. Nat. 



Daphnoides on Cladoc^res, 31. Edwards, Hist. Nat. Brust., lii. 372. 



Lucas, Exp. Sc. de I'Algine. 



Characters. — This tribe which corresponds with the order Cladocera of Baird 



and some recent authors, is characterised as having the whole 



