Vol. 54.] MISS J. DONALD ON THE GENUS ACLISINA. 57 



Locality and Horizon. — My own collection contains five specimens 

 from the Lower Carboniferous of Peuton, the largest of which con- 

 ;sists of twelve whorls, whose length = 6 mm. The specimen figured 

 (PI. Ill, fig. 12) has the surface better preserved ; its apex is broken, 

 and only nine whorls remain, of which the length =5 mm., width = 

 barely Ig mm. Other examples occur in the Lower Limestone Series 

 {(P) at Law, Dairy ; Capelrig ; Craigenglen ; Cunninghambaid- 

 land ; High Blantyre ; and Brankam Hall. There are several frag- 

 ments of this species in lire's collection at the Royal Society's 

 rooms, Edinburgh. A specimen (PI. Ill, figs. 13, 14 a, 6 & c) from 

 Law, in the collection of Dr. Hunter-Selkirk, is remarkable for 

 having the protoconch preserved, but the surface is much worn; 

 it consists of thirteen whorls in a length of barely 4| mm., and 

 its width equals rather less than 1 mm. An individual from the 

 same locality in Mr. Bennie's collection consists of fourteen whorls ; 

 its length is nearly 4-i- mm. Though the aperture is very imperfect, 

 it appears to give evidence of the reflection of the inner lip on the 

 bodj^-whorl. 



This species also occurs in the Upper Limestone Series {d^) at 

 Olencart, Dairy. 



There is a distinct variety which has a smaller spiral angle and 

 more elongated form, for which I would suggest the varietal name 

 dubia. The largest specimen of it figured (PI. Ill, fig. 15) is from 

 ■Craigenglen, in the collection of Mr. Thomson ; it has seven whorls 

 preserved, the apex being broken, and measures 6| mm. in length 

 and 2 mm. in width. I have a much smaller example in my own 

 collection from the neighbourhood of Glasgow : its length = 2| mm., 

 width = I mm. ; it shows the reflection of the inner lip. These 

 specimens, as well as others from East Kilbride and Cunningham- 

 baidland, occur in the Lower Limestone Series (d^). 



A small fragment from the Upper Limestone Series, Glencart, 

 which is probably this variety, has a portion of the protoconch 

 preserved ; it shows that the ornamenting threads commence on the 

 conch immediately after its junction with the protoconch. 



AcLisiNA siMiLis, sp. nov. (PI. Ill, fig. 16, & PI. IV, fig. 1.) 



Description. — Shell elongated, conical, composed of more than 

 -eight whorls. Whorls increasing gradually, flattish in outline, 

 barely convex. Ornamentation consisting of five strong threads 

 near the middle of the whorl, and two or three finer ones below, 

 with several additional fine threads on the body-whorl; the spaces 

 between the strong threads are the widest. Sutures moderately 

 deep. Aperture subovoid. Columella simple, nearly straight. 

 Base convex, imperforate. 



Hesemblances. — This species bears some likeness to A. pulchra in 

 the character of the ornamentation, but it is distinguished by its 

 more elongated form, flatter whorls, and smaller spiral angle. 



Dimensions. — There are six specimens in Mr. Bennie's collection. 

 The largest (PI. IV, fig. 1) has both apex and base broken, leaving 



