1909. RiDDELL. — Spinther 07iiscoides, Johiston. 105 



Lamella. — Another point to which v. Graff has attached 

 some importance is the diflference, in the various species, of 

 the shape of the transverse section of the lamellae. In 

 6". viiJiiaceiis a typical lamella begins, next the middle line, 

 as a simple fold. As we trace it outwards, the top of this fold 

 curves over, another edge becomes developed, and finally at 

 the outer edge the lamella show\s a Y-shaped section. In 

 5. oiiiscoidcs (v. Graff) the shape is that of a Y with a broad 

 stem and shallow top, the depressed surface of the top being 

 tuberculate. M}^ specimens show no trace of such a gradation 

 as occurs iu vS*. 7niniaceus^ the general plan closely resembling 

 the appearance seen in v. Graff's kS. oniscoidcs. 



Extruded pharynx. — This is figured by v. Graff in 

 6". arctictis as rosette-shaped, while he describes his S. oiiiscoides 

 as resembling kS'. <7;'6"//«^5. In 6". miniaceiis hoWi v. Graff and 

 M'Intosh (9) figure the extruded phar3^nx as trumpet-shaped. 



In ni}^ examples the pharynx, wherever it was found 

 extruded, was always rosette-shaped. 



Intestine. — The mid-gut in Spinther is provided with 

 paired diverticula, which in S. vimiacais have a fairly wide 

 communication with the gut. In this species the dorsal 

 caecum is also provided with paired lateral diverticula, 

 corresponding in position with the diverticula of the mid-gut. 

 The caecum has no lateral diverticula in either v. Graff's 

 ^. oniscoides or S. arcficus. Of the mid-gut diverticula in 

 these two latter species v. Graff says : — " Their width is, on 

 the contrary, very considerable, quite in opposition to the gut, 

 which appears narrow and considerably compressed from 

 above downwards. The diverticula are attached to it like 

 expanded sacs." This appearance is shown in Plate i 

 (fig. 9), which shows the shape as figured by v. Graff. In the 

 shape of the diverticula, and of the gut itself, my specimens 

 differ from v. Graff's S. o7iiscoides, resembling rather S. mmi- 

 aceus (see fig. 6.) There is no apparent compression of the 

 mid-gut, nor are the diverticula of the shape described by 

 V. Graff. 



In none of my sections, either transverse or longitudinal, 

 have I been able to detect any trace of diverticula from the 

 caecum. 



