276 SUMMAKY OF CUKKENT EESEAECHES KELATING TO 



granitic region with little chalk, craytishes are of rare and very local 

 occurrence, e.g. near Sussac. It is interesting to find that the occur- 

 rence of crayfish in this region coincides very exactly with the 

 occurrence of amphibolites, which include 13-23 p.c. of chalk. 



J. A. T. 



Terrestrial Isopods of Natal. — W. E. Collinge {Annals Natal 

 Museum, 1920, 4, 471-90, 6 pis.). Descriptions of new species of Ligia, 

 Allonisciis and Guharis, and the establishment of a new genus Anchi- 

 cubaris, separated from Guharis on account of the form of the pleural 

 plates of the mesosome and the greatly produced anterior margin of the 

 cephalon. J. A. T. 



Parcorophium excavatum in Brisbane River. — -Chas. Chilton 

 {Mem. Queensland Museum, 1920, 7, 44-51, 19 figs.). A note on the 

 occurrence of this New Zealand Amphipod in the Brisbane River, 

 Australia. A description is given. The genus, of which this is the 

 only species, comes close to Corophium, but the mandible has the palp 

 well-developed and three-jointed ; the second gnathopod of the male is 

 markedly different from that of the female ; in both sexes the second 

 gnathopod has the merus produced into a scoop-like process different 

 from that in Corophium ; the third uropods are two-branched. J. A. T. 



Genetics of a Daphnia Hybrid during Parthenogenesis. — W. E. 

 Agar {^Journal of Genetics, 1920, 10, 303-30, 3 figs.). On the 

 hypothesis, now supported by a mass of indirect evidence, that segrega- 

 tion of hereditary factors is due to the segregation of homologous 

 chromosomes in meiosis, it is clear that there should be no such segrega- 

 tion in parthenogenetic reproduction uuaccompanied by reduction of 

 the chromosomes. A hybrid clone, derived from a cross between 

 Daphnia ohtusa and D. pulex, was bred for ten generations. Through- 

 out this period the hybrid clone was characterized by excessive produc- 

 tion of males and sexual eggs, complete sterility of the males, partial 

 sterility of the parthenogenetic eggs, and probably normal fertility of the 

 sexual eggs. The ten parthenogenetic generations of this clone fur- 

 nished no evidence of the occurrence of cegregation. This experiment 

 is complementary to Agar's former experiments on inheritance in ])ar- 

 thenogenesis in the Cladoceran Simocephalus, and indicates that during 

 the parthenogenetic reproduction of these forms, which is not accom- 

 panied by reduction of chromosomes, Mendeliau segregation does not 

 take place, nor does genetic diversity between parent and offspring 

 normally arise. J. A. T. 



Swedish Silurian Cirripedia. — J. C. Moberg (Limds Universitets 

 ArssTcrift, 1915, 11, No. 1, 1-20, 2 pis., 2 figs.). Descriptions of some 

 new forms, e.g. Lepidocoleus suecicus sp. n,, and Plumidites dalecarlicus 

 sp. n., and a discussion of primitive Cirripedia. J. A. T. 



Annulata. 



Ciliated Crown of Trochosphere of Protula meilhaci. — A. 

 Soulier {Arch. Zool. Exper., 1920, 59, Notes et Revue, No. 1, 1-4, 



