Over den hele arktiske Zone synes denne Art at 
være talrig udbredt i de middelmaadige Dyb. Prof. Leche 
angiver den fra det Kariske Havl. 
Hvorvidt Cingula Jan Mayeni, Verrill er vor Art, 
betvivler jeg. Prof. Verrill har været saa venlig at sende 
mig Exemplarer af den amerikanske Form, men disse 
adskiller sig fra vor ved en paafaldende grovere Sculptur. 
Spiralribberne er saaledes kun 3 til 4 og af betydelig 
Styrke, hvorved Skallen faar Udseendet af at være 3—4 
carineret. Ved at sammenligne Verrills Tegning (Cat. 
Mar. Moll. 1882, Pl. XLII, Fig. 8) med vor, vil denne 
Afvigelse være iøinefaldende. For at adskille disse to For- 
mer vil jeg derfor foreslaa Rissoa americana for den ameri- 
kanske Form. 
Rissoa (Cingula) islandica, n. sp. 
Tab. XI, Fig. 8, 9. 
Skallen gjennemsigtig hvid, svag glindsende, cylindrisk 
conisk, Vindingerne 5 svagt convexe, Suturen dyb; Mund- 
aabningen omtrent %/; Del af Skallens Længde, rund oval, 
noget udvidet nedad og noget skjæv; ydre Læbe noget for- 
tykket, den indre vel udviklet og sammenhængende; der er 
en tydelig Umbilicalsplit. Seulpturen bestaar af yderst 
fine, næsten microscopiske Spiralstriæ og svage, men tætte 
Veekststriber; Apex er stump, glat og glindsende. 
Størrelse: 2*/,7" Axiall., 11/57" Diam. 
Forekomst: St. 48—299 Fayne. 1 levende Expl. 
Dr. Jeffreys antog vor Art for muligens at være en 
Dybvandsyvarietet af Rissoq arenaria, men denne Anskuelse 
kan jeg ikke dele, da den forekommer mig altfor afvigende 
baade i Form og Sculptur. Cingula leptalea, Verr., synes at 
staa den meget nær, men Mundaabningens Form er afvigende, 
Rissoa (Setia) Griegi, Fr. 
Tab. XI, Fig. 10. 
Rissoa Griegi, Friele, Jahrb. Mal. Gesell. 1879, Pg. 274. 
Skallen rund oval, næsten globos, gulagtig, Vindin- 
gerne 4 tumide. raskt tiltagende, Spiret kort, Suturen dyb; 
1 Herzenstein (op. c. Pac. 682) angiver den fra det hvide Hav. 
This species appears to be abundantly distributed 
over the whole arctic zone, in moderate depths. Prof. 
Leche states it as pertaining to the Kara seal. 
I have some doubt whether Cingula Jan Mayeni, 
Verrill, is our species. Prof. Verrill has kindly sent me 
specimens of the American shell, but it is distinguishable 
from ours by a strikingly coarser sculpture, The spiral 
ribs are, for instance, only 3 to 4 in number and of consider- 
able strength, owing to which fact the shell acquires the 
appearance of being triply to quadruply carinated. On 
comparison of Verrills illustration (Cat, Mar. Moll. 1882, 
Pl. XLII, fig. 8) with ours, this divergence becomes im- 
mediately apparent. In order to distinguish these two 
forms I would, therefore, propose as an appellation for 
the American form, Rissoa americana.. 
Rissoa (Cingula) islandica, n. sp. 
Pl. XI, figs. 8, 9. 
The shell translucently white, faintly lustrous, cylin- 
dric-conical; 5 faintly convex whorls; the suture deep; the 
aperture measuring about three-sevenths of the length of the 
shell, subeireular, somewhat dilated outwards and a little 
oblique; the outer lip somewhat thickened; the inner lip 
well developed and continuous: there is a distinet umbili- 
cal fissure. The sculpture consists of extremely fine, almost 
microscopical, spiral striæ, and of faint, but close lines, of 
growth, Apex, obtuse, smooth and lustrous. 
Size: Axial length, 2.57”, Diam, 1.57”, 
Habitat: Stat. No.j48. Depth, 299 fathoms. One 
living specimen. 
Dr. Jeffreys considered our species to be, probably, 
a deep-water variety of Rissoa arenaria, but I cannot share 
that opinion, as it appears to me to be too divergent both 
in form and sculpture. Cingula leptalea, Verr. appears to 
be related to it, but the form of the aperture differs. 
Rissoa (Setia) Griegi, Fr. 
PI. XI, Fig. 10. 
Rissoa Griegi, Friele, Jahrb. Mal. Gesell, 1879, pag. 274. 
The shell subcircular, almost globular, yellowish; 4 
tumid, rapidly increasing, whorls; the spire short; Suture 
' Herzenstein (Op. c. pag. 682) states that it pertains to the 
White Sea. 
