PEILE : SOME NOTES ON RADULJE. 17 



Fig. 1. — Columbarium pagoda (Lesson). X 230. 



Fig. 2. — Cyprcea caput-serpentis, Lin. x 53. (a) normal, (b) abnormaL 



Fig. 3. — Potamacmcea fluviatilis (Blaniord). x 110. 



Fig. 4. — Patella perplexa {Fi\shvy). x 110. 



Fig. 5. — Minolia {t) philippensis, Watson, (a) parts of two rows of the 



radula. x 110; (6) mandible X 53. 



Fig. 6. — Olivella nympJia, Adams & Angas. x 230. 



Fig. 7. — Belloliva brazieri (Angas). x 230. 



Fig. 8. — Microvoluta australis, Angas. x 470. 



Patella perplexa would therefore fall in the section Scutellastra 

 (H. & A. Adams), as defined by Pilsbry, loc. cit., p. 94. The shell 

 which provided our radula is completely covered with an evenly 

 spread coralline growth. If its habit is to be so covered, this, 

 coupled with its station being below ordinary low -water mark, 

 may account for the animal remaining so long unknown though 

 dead shells are common on New South Wales beaches. 



2. One of the most interesting finds among the Twofold Bay 

 material has been that of two species of Minolia (?), viz. philippensis, 

 Watson, and fulcherrima, Angas, with very close afiinity to 

 MachcBToplax (olim Solariella) of Northern Seas. Although the 

 shells of philippensis and pulcherrima difier so that the two species 

 might well be ascribed to different genera, the radulse and mandibles 

 agree in every particular so far as can be judged in these small 

 specimens which are anasually hard to disentangle. (Fig. 5, 

 a and b.) The marginals naturally fold inwards so as to cover the 

 rest of the teeth, and it is very difficult to spread them outwards 

 without breaking up the specimen. However, after examining 

 two specimens of each species I am able to determine the following 

 points : — 



(a) The rhachidian and laterals differ only in minor details from 

 those of Machcsroplax varicosa, Mighels, as represented in the 

 Gwatkin collection and as figured in Thiele, vol. ii, pi. xxv, fig, 11. 



(6) The sickle-shaped marginals are more slender than in 

 M. varicosa, but, like them, diverge from the typical rhipidoglossate 

 form. 



(c) Locking with the bases of the marginals is a row of broad 

 plates, very difficult to distinguish from the adjacent teeth. I have 

 been unable to locate such plates in the species of Machceroplax 

 I have examined. 



Both radulse are comparatively broad and short, with about 

 thirty rows of teeth. A Gwatkin slide of Minolia (?) congener, 

 Sowerby, from South Africa, shows a radula of similar type. 



Living alongside the above-mentioned Australian species is 

 Minolia (?) angulata, auctt. The shell of this does not appear 

 to differ greatly from, that of a young M. philippensis. The radula, 

 however, is of quite a different type, resembling that of Ethalia, 

 with degenerate rhachidian and laterals and with marginals of a 

 more normal rhipidoglossate form. Most of the species in the 



VOL. XV. — APRIL, 1922. 2 



