314 Point Levi Fossik, 



M, glohosus and this latter leads us through A. suhclavatus to A, 

 cylindricus* 



This latter appears to me to be an Arionellus, The speci- 

 mens are too imperfect to enable me to prove whether or not 

 our four species belong to two distinct genera or one only. I 

 shall place the two most convex forms in Menocepkalus and the 

 other two in Arionellus. 



Arionellus cylindricus. N. s. 



Fig. 14. Fig. 15. 



Fig. 14. — Arionellus cylindricus. 



Fig. 15. — Arionellus suhclavatus : a, side view of the glabella. 



Description, — Glabella sub-cylindrical slightly narrowed from 

 behind forwards, the sides nearly straight and separated from the 

 very prominent cheeks by a deep furrow ; the front obtusely 

 rounded or nearly straight. The neck furrow is deep and rounded 

 and the neck segment well defined but apparently not very pro- 

 minent. The posterior glabellar furrow is well defined all across, 

 parallel with the neck furrow for half the width of the glabella 

 and then directed obliquely forward on each side at an angle of 

 45"; it is about its own width distant from the neck furrow. 

 The next furrows forward are situated a little in advance of the 

 mid-length of the glabella ; they are slightly oblique and their 

 inner extremities are separated by about one third the width of 

 the glabella. In front of these are two other furrows on each 

 side very inconspicuous and not always visible. The anterior 

 margin of the head consists of a narrow elevated ridge separated 

 from the front of the glabella by an angular groove of about its 

 own width. From the summit of the terminal ridge the margin 

 descends with an abrupt slope so that on a front view the head 

 appears to be bounded by a flat nearly vertical band, the width 

 of which is equal to rather more than one half the elevation of 

 the glabella. The surface appears to be smooth or finely granular. 

 Eyes, fixed cheeks, thorax and pygidium unknown. Length of 

 longest head seen three and a half lines ; width of glabella about 

 two lines at neck segment and a little less at the anterior ex- 

 tremity. The form of the glabella of this species is almost exactly 



