whorls is crossed 1 »\ faint spirals, 2 in number on penultimate, about 1 



last whorl, of whicli latter the upper ones are more umus, bead-like 



the riKs, those on the canal plain, lastly the whorls are crossed bj growth-lines. 



tel) oval, angular above, with a short, wide canal below; peristome thin, broken, 



rowth-lines with a wide, rather deep sinus above, then considerably protracted, 



ar side concave above, slightly tortuous below, with a conspicuous, appressed layer 



namel. 



Ali B . lal apert. alt. 3 % lat. i 8 / 4 MUI. 



Though small, 1 t hink this form to be distinct and nol to be identified with the young 

 iny described species. 



14. Surcula sp. 



Stat. 178. 2° 40 .;;■.; E. 1 eram-sea. S35 M. Blue mud. 2 Spec. 



These specimens are nearly allied to the preceding species, they are a little narrower 

 and the infrasutural rib is less developed and has only few tracés of the folds, as the specimens 

 ver) young, 1 think it is not advisable to name or describe them, they may belong to a 

 slight variety of the former. 



15. Sur at la Nierstraszi n. sp. PI. XXVIII, fig. 6. 



Stat. 271. 5^4'V.jS., 136° o' K. Arafura-sea. 1788 M. Bluish green mud. 1 Spcc. 



Shell broadly fusiform, with rather short spire, thin, light greyish-white. Nucleus wanting, 

 remaining whorls nearly 6, of which the upper one is likewise eroded, angularly convex, slightly 

 excavated below the deep suture. Sculpture consisting of slightly oblique, narrow ribs, arcuated 

 in the excavation, 15 in number in penultimate whorl, with blunt tubercles about the median 

 part of upper whorls and on shoulder of last whorl, with beads at thcir upper extremities ; 

 just below the suture, the shell is covered with fine growth-striae and spiral lirae, these lirations 

 being faint in the excavation, stronger and crowded in lower part of whorls, more remote on 

 canal; last whorl attenuated below, passing without marked limit in the rather short canal. 

 Aperture oval, slightly angular above, with a rather narrow canal below: peristome broken, 

 according to growth-striae with a very shallow sinus below the suture; columellar margin concave 

 above, directed to the left along the- canal, with a thin layer of enamel. 



( >perculum thin, corneous, with a terminal nucleus at the left side. 



Alt. 25'/,. lat. I2 1 /,-. apert. alt. 14, lat. 5 MUI. 



Radula with 2 rows of teeth, in about 12 transverse rows, each tooth c with a rather 

 sharp point and a deep sinus at its basal margin, separating 2 unequal digitations. 



The shell was of rather obscure nature, scarcely any tracé of a sinus was visible and 

 it' at all by the aid of the growth-lines, it is very unsignificant, the operculum is not characteristic 

 tor tl after I had seen the radula, 110 doubt was left about its belonging to the Pleuroto- 



and by its sinus it 1 ■ ches Surcula, though the teeth resemble those of 



64 



