120 Dr. W. B. Benham on the 



ilie modern Australian molluscan fauna. A search among 

 the more persistent of living types may produce some torn 

 pages of its history. One such is recognized by the writer in 

 Lucapinella, whose occurrence in Australian waters is noted*. 

 But palaeontology must be chiefly called on to relate the story 

 of the decline and fall of the Antarctic marine fauna. 



XV. — The Male of Apus cancriformis. By W. Blaxland 

 Benham, D.Sc. (Lond.), Hon. M.A. (Oxon.), Aldrichian 

 Demonstrator in Comparative Anatomy, Oxford. 



In view of the rarity of the male individuals of this interesting 

 Phyllopodan Crustacean, it may be worth putting on record 

 the occurrence of one amongst the specimens of Apus used 

 for examination in the ordinary course of our work in the 

 Zoological Laboratory here in Oxford. The specimens were 

 obtained through Fric, of Prague, from Podebrady, a town 

 on the Elbe. 



Apus is one of the stock examples of parthenogenesis, the 

 bulk of the individuals being females ; that males do occur 

 occasionally we know from the observations of Kozubowski, 

 von Siebold, and others ; but locality and season appear to 

 have considerable influence on their occurrence. Thus, in 

 1858, out of 549 specimens of Apus collected at Krakau, as 

 many as 154 were males, whereas in 1866 out of 999 col- 

 lected at Breslau there were only 7 males. Von Siebold's 

 repeated endeavours during several successive years to obtain 

 males are matters of history. 



The credit of first describing the male is due to Prof. Kozu- 

 bowski, who, in 1857, gave an account of the testis, sperm- 

 duct, and spermatozoa (Arch. f. Nat. xxiii.), and laid the 

 foundation for the view which has since then been nearly 

 universally adopted, viz. that Apus is parthenogenetic. Up 

 to that period it had been considered hermaphrodite. 



It will not be amiss to note that the only external point of 

 difference between the two sexes is the absence in the male 

 of that modification of the sixteenth appendage which results 

 in the female in the formation of an egg-pouch (" oostego- 

 pod ") ; in fact, the sixteenth appendage of the male is 

 precisely like its neighbours, and at its base the sperm-duct 

 opens. 



I looked carefully for any appendages which might be 



* Proc. Roy. Soc. Vict. 1894, p. 197. 





