i 



ZOOLOGY. AND BOTANV, MICROSCOPY, ETC. 35> 



7- G-astropoda. 



New Chitons. —Edwin Ashby {Trans. Proc. R. Soc. S. Australia, 

 li:>l'.). 43, GG-7r), 1 pi.). Definition of a new sub-genus, Zostcrkola, 

 differing from Stenorhiton {sensu stricto) in that the shell is short and 

 broad instead of being elongated and narrow. It possesses the highly- 

 polished and unscniptnred surface and minute girdle-scales so distinctive 

 of the true Steiior.hitdit, and it lives on the same plants, the sea-grasses. 

 The new sub-genus is erected for the reception of Stcnochiion pilshry- 

 aiius Beducdl. K description is ako given of Kopion-ella g.n., which 

 differs from Plaxiphora in having peculiar oar-headed girdle bristles or 

 spicules, and an elevated recurved tail-valve with terminal mucro ; and 

 from Frenibleyana in the peculiar bristles and in the slits in the median 

 valves being centrally situated, and in the sinus being much narrower, 

 especially in the tail-valve. J. A. T. 



New Australian Chitons. — Edwin Ashby {Trans. Proc. R. Soc. 

 S. Anstralia, 191'.t, 43, ;;9-4-404, 2 pis.). Descriptions of Xotoplax 

 porcina sp. n., from Gulf St. Vincent ; Acanthocliiton niaxiUaris sp. n., 

 from S. Australia, a beautiful and striking form with a row of excep- 

 tionally large milk-white pustules, suggesting a row of rounded teeth set 

 in a jaw ; ^4. gatUffi, sp. n. ; and two new sub-species of Call isto chiton 

 antiqaus. ' J. A. T. 



Revision of Genus Loricella. — Edwin Ashby {Trans. Proc. R. 

 Soc. Victoria, 191'J, 43, r)9-(;r), 1 pi.). A description of the two species 

 of this genus of Polyplacophora — L. angasi H. Adams and Angas, and 

 L. torri sp. n., both Australian. The genus may be near Lorica, as is 

 suggested by the cleft in the girdleand by the character of the tail-valve, 

 but its large head and the small foot, together with its markedly distinct 

 girdle, suggest that the relationship may be more superficial than real. 

 The girdle is clothed with peculiar bilobed scales, like grains of wheat 

 set on end, either transparent and glassy or opaque white. Between 

 these there are strange "spear-heads," which push through to about 

 eight times the length of the scales. They look hke cylindrical 

 pointed spear-heads of porcelain. They grow into coarse hairs or tubes, 

 and give off more " spear-heads " as buds. A single stalk may have as 

 many as six " spear-heads," Their function is obscure. J. A. T. 



Spermatogenesis in Gastropods. — Victor Schitz {Arch. ZooJ. 

 Exper., 1920, 58, 489-520, 12 figs.). In Cerithium, Bittium, and 

 TurriteUa there is a typical and an atypical spermatogenetic cycle, the 

 latter resulting in spermatozoa with a bundle of long cilia. In the 

 typical cycle the chromatin forms the head ; in the atypical it degene- 

 rates and disappears. In the atypical cycle the role of the idiozome 

 remains obscure ; in the typical cycle it serves as a " vehicle " for the 

 transport of the anterior pole of the nucleus of the spermatid, the deri- 

 vative of the central corpuscle. It afterwards slips along -the tail with a 

 blob of protoplasm and disappears. The idiozome is the same as the 

 " nebenkern " of Pulmonates ; it is not mitochondrial in origin, as 



D 2 



