68 MISS J. DONALD ON ACLISOIDES. [Feb. 1 898, 



figured (PI. V, figs. 7 & 7 «) to show the lines of growth. In the 

 British Iklnseum (Nat. Hist.) there is a portion of a shell from Settle 

 consisting of four and a half whorls : also three specimens of which 

 the locality is not known : they bear a great resemblance to the 

 other example, and are probably from the same place. 



This species also occurs in the Lower Limestone Series (d^) at 

 Craigenglen, and in the Upper Limestone Series {d^) at Glencart, 

 Dairy. These shells are much smaller than the English and 

 Belgian specimens. One (PI. Y, figs. 8 & 8«) from the former 

 localit}^ is remarkable for having the protoconch entire ; the apex is 

 somewhat worn, so that the junction of the protoconch is not very 

 distinct, and the point of commencement of the ornamentation is 

 not shown. 



De Koninck states that this species also occurs at Gare, Orchard, 

 llobroj'ston, Swindridge, and Auchenbeg, but I have not met with 

 it from any of these places, and I therefore think that he has 

 probabl}" confounded it with Aclisina pulchra, var, tenuis, of which 

 I have seen specimens from the three latter localities. 



Tn Belgium it is found at Yise (Assise YI), from which locality 

 there are examples in the British Museum (Nat. Hist.), Brussels 

 Museum, Liege Museum, and the collection of M. Destinez at Liege. 



The validity of this species rests upon the examination of about 

 thirty specimens. 



AcLTSOiDES STEIATULA, var. Armsteongiana. (PL Y, figs. 9 & 10.) 



Description. — Shell elongated, conical, composed of about eight 

 whorls. These are flat above, convex below, slightly angular a little 

 below the middle. Whorls ornamented by about nine nearly 

 equal raised threads separated by equal spaces, with several addi- 

 tional threads on the body-whorl ; two or three of the upper threads 

 are absent on some specimens. The lines of growth curve back- 

 ward above, form a sinus of moderate depth, and then curve 

 forward below. The sinus is situated on the widest part of the 

 whorl, in the space occupied by three of the threads, there being a 

 thread on each side of it and one down the middle. Sutures deep. 

 Aperture longer than wide. Columella nearly straight, slightty 

 thickened. Base convex. 



Resemblances. — This shell resembles A. striatula so much that I 

 am more inclined to regard it as a variety of that species than as a 

 distinct species itself. The general form of the whorls and sinus 

 are similar. It differs in the whorls being rather more angular and 

 prominent in the middle, in having deeper sutures, and in the 

 ornamenting threads being equal in stj'ength with the exception of 

 those bordering the sinus, which are generally slightly sLronger. 

 This species is also somewhat like Murchisonia dcdryensis, Don.,^ in 

 the contour of the whorls, but the ornamenting threads are differently 

 disposed. An enlarged portion of a whorl of M. dairy ensis is figured 

 (PI. Y, fig. 11) for comparison. M. dcdryensis ^idho^ly has greater 



1 ' Notes on the Genus Mnrchii-onia & its Allies,' Quart. Journ. Geol. Soc. 

 Yol. li (1805) p. 224 & pi. ix, fig. 3. 



