238 



Australia. I believe the type was from the former State, and therefore suggest that 

 the form noted from King Island (Ashby and Hull, Austr. Zool., vol. iii., pt. 2, 

 March, 1923) as having shorter spicules, more widely spaced and proportionally 

 stouter, than typical C. striatus from South Australia, be recognized as Reeve's 

 var. giinni. In the same paper we noted that the granulose character of the 

 juvenile shells from King Island was changed into ridges at a rather earlier 

 stage than is common in typical specimens of C. striatus. I consider this variety 

 is common to both King Island and Tasmania. 



Cryptoplax striatus, Lam., var. westernensis, n. var. 



In October, 1920, the writer collected at Rottnest, Western Australia, a 

 single specimen of Cryptoplax that differs slightly from C. striatus. The speci- 

 men measures 35X15 mm.; valves 5, 6, 7 are slightly spaced, all are strongly 

 beaked. I referred this specimen to C. striatus (Trans. Roy. Soc. S. Austr., vol. 

 xlv., 1921, p. 45). It differs from the typical shell in that it shows no sign of the 

 granulose sculpture of the juvenile form, and seems, from the start, to com- 

 mence the coarse, longitudinal ridges, also the spicules on the girdle are both 

 shorter and more slender than in C. striatus proper. It seems in some respects 

 to be intermediate between C. striatus and the form with very short, hair-like 

 spicules, which we have for so long incorrectly called C. gunni of Reeve, but 

 the character of the spicules is nearer C. striatus. This was probably the shell 

 from Western Australia referred to by Thiele as C. gunni and by Torr as 

 C. striatus. 



I therefore suggest that this western form be distinguished as a variety 

 of C. striatus under the name of C. zvesternensis, Ashby. 



Cryptoplax iredalei, n. sp. 

 PI. xix., fig. 4. 



Reference has been made to a Cryptoplax that has been referred to as 

 C. gunni, Reeve, by most writers. My examination of the type, in company 

 with Mr. Iredale, effectually disposes of that determination and leaves this 

 Crytoplax without a name. Mr. Iredale has for some years been aware that 

 this shell was' not C. gunni, but until the rediscovery of Lamarck's types (before 

 referred to) it was still an open question as to which of our known species were 

 conspecific with Lamarck's shells. I promised to leave this species to Mr. 

 Iredale for naming, and therefore will content myself with a short definition, 

 sufficient for the purposes of this paper. (Note. — As more than a year has 

 elapsed and this species seems still without a name, I propose to call it after 

 Mr. Iredale. I had hoped prior to the reading of this paper to have received 

 his approval of this action.) 



The valves in this species may be slightly narrower and longer than C. 

 striatus of the same size — the juvenile is similarly granulose in sculpture — but 

 in what may be termed semi-adult specimens there is usually a space between 

 the 5th and 6th valves, and in very large specimens — one before me measuring 

 95 mm. in length (dried) — there is a short space after the 3rd valve and a wide 

 space after valves 4, 5, and 6. 



The distinguishing character is found in the girdle, which is usually banded 

 in very pretty shades of rich brown and grey. The spicules are very dense, but 

 so minute and slender as to be overlooked altogether without the aid of a good 

 pocket lens. 



Habitat. — I have taken it at Port Lincoln and in many places on the Gulf 

 of St. Vincent, and Mr. W. L. May has taken it in north-western Tasmania. 



