SCIENCE-GOSSIP. 



15 



ARMATURE OF HELICOID LANDSHELLS. 



By G. K. Gude, F.Z.S. 



(Continued from Vol. iv. p. 285^. 



A FEW more species of Plectopylis remain to be 

 "^ described and figured. Their consideration 

 has been delayed on account of authentic specimens 

 being inaccessible to me ; in one case no figures 

 have yet been published, while in another case, 

 where the species is supposed to have been illus- 

 trated, the figures represent another form. These 

 are Plectopyiis repercussa, P. anguina, and P. rejuga, 

 all described by Dr. A. A. Gould. In the present 

 instalment I will discuss P. refjiga together with 

 P. leiophis, which has been confused with it in some 

 quarters, leaving P. repercussa and P. anguina, and 

 sundry other allied species for consideration in 

 future instalments of these papers. Plectopylis reper- 

 cussa has recently been regarded as synonymous with 

 P. achatina, but whether justly so or not, it was 



p. 99. This species has not hitherto been illus- 

 trated, as the figures given by Philippi, by Reeve, 

 and by Kiister were taken from the specimens in 

 Cuming's collection, now in the British Museum, 

 and these specimens, although labelled P. rejuga, 

 are not that species, but P. leiophis, as careful 

 comparison with Mr. Benson's type specimens has 

 convinced me. I have been unable to obtain any 

 specimens of P. refuga, and I am therefore com- 

 pelled to rely upon Dr. Gould's description, 

 supplemented by the notes and sketches by Dr. 

 Bagg, and by the photographs now reproduced. 

 Dr. Gould described the shell as " sinistrorse, 

 discoid, flat above, concave below, greenish- 

 corneous; whorls, six, closely coiled, thickly 

 striated, the last deflexed near the aperture ; 



S {K3 



Fig. 75. — Phctopylis refuga. 



impossible for me to decide, as the type specimens 

 of the former, as well as of the other two species, are 

 in the possession of the New York State Museum, 

 Albany, N.Y., and my request for the loan of them 

 was referred to the Trustees, who decided not to let 

 the specimens go out of the country. The Director, 

 Dr. Merrill, however, very obligingly had the shells 

 photographed and their armatures sketched for 

 me. I have thus the pleasure of being able to lay 

 authentic figures before my readers. I am much 

 indebted to Dr. Merrill, as well as to Dr. Bagg, 

 his assistant, who made the sketches and furnished 

 valuable notes, which, together with the photo- 

 graphs, enabled me to clear up the doubtful points 

 in connection with the three species in question. 



Plectopylis refuga (figs. 75^-^), from Tavoy, Burma, 

 was described by Dr. Gould in the "Proceedings 

 of the Boston Natural History Society," ii. (1846), 



June, i8g8. — No. 49, Vol. V. 



suture impressed ; aperture very oblique, heart- 

 shaped ; peristome white, reflexed, connected by a 

 sinuous callus ; a white flexuous plate revolving in 

 the penultimate whorl." He further remarks that 

 " this remarkable shell is almost exactly like Helix 

 carahinata. Per. [Corilla rivolii, Desh.] , except that 

 it is reversed, and has no lamellae revolving within 

 the outer lip." From the abo\e description it is 

 impossible to know which form Dr. Gould had 

 before him, as it applies equally to several distinct 

 shells. 



The following notes have been communicated by 

 Dr. Bagg : "Helix refuga, Gould, catalogue number, 

 271 ; original number, A 562. Two earliest volu- 

 tions smooth, remainder of shell very finely striate 

 and hairy. Outer volution on lower side angular. 

 Greater diameter nearly f inch [= 19 millimetres] ; 

 smaller diameter, ^g. inch [= 14 millimetres]; alti- 



'A' /(; 



n. 



