246 EEY. B. "BOOG WATSON ON THE 



Mouth rattier small, rhomb oidal, having an acute angle above and 

 at the point of the pillar, and an obtuse angle at the corner of 

 the base and at the top of the pillar. Outer lip very thin and 

 sharp ; it joins the body just at the circumbasal angulation, and 

 springs at once very much forward, so as to form with the body 

 a small, shallow, but acute-angled sinus ; with a slight and regular 

 forward curve it thus advances to the angulation of the base, 

 from which it runs straight, flat, and slightly patulous to the 

 point of the pillar, which it joins at a bluntly-acute angle, form- 

 ing a slight but not at all incised canal. Pillar is not at all 

 oblique, but is very slightly concave. Inner lip is entirely discon- 

 tinuous across the body, and first makes its appearance in a small 

 and slight porcellanous pad, which closely encircles the base of 

 the pillar ; its sharp-edged, narrow, and slightly patulous face 

 forms the entire pillar. Umbilicus lies behind the thin pillar-lip, 

 and is a distinct, little, pervious, funnel-shaped pore, sharply de- 

 fined by the intrabasal carination. H. 0*62. B. 0'2. Penulti- 

 mate whorl, height 0-083. Mouth, height 0-12, breadth 0-088. 



I doubt very much whether this species really belongs to this 

 genus. From Sars's Hemiaclis it seems, judging from his diagnosis 

 and excellent drawings, to be distinguished by the thinness of 

 the spire and by the minuteness of the apes, the size of the umbi- 

 licus, and the smallness of the mouth; in doubt, therefore, I 

 accept Dr. Gwyn Jeffreys's advice, and classify it as an Aclis, a 

 convenient, because somewhat vague group. I have said that the 

 shell is broadly subulate. The measurements show very plainly 

 that it is so only relatively to its fellows in the genus. 

 2. Aclis hyalltsta, n. sp. 



St. 122. Sept. 10, 1873. Lat. 9° 5' S., long. 34° 50' W. Off 

 Pernambuco. 350 fms. Mud. 



Shell. — Broadly subulate, high, conical, umbilicate, ribless or 

 very faintly ribbed on the earlier whorls, thin, glassy. Sculpture. 

 Longitudinals — there are very many, close-set, faint, irregular 

 angulations of the surface, which, besides, is covered with very fine 

 hair-like striae ; these under a lens look very sharp and regular, 

 but under the microscope are seen to be rounded and irregular, 

 made up of little inconstant curves, with changing swellings and 

 depressions. Spirals — the surface is faintly malleated in a some- 

 what orderly fashion ; but besides the larger system of malleations 

 there is a second system a good deal smaller and more irregular, 



