94 PROCEEDINGS OF THE ACADEMY OF [Vol. LXXV 
The last whorl is bluntly subangular in front, or at least some- 
what compressed there; it descends rather deeply to the aperture. 
Aperture is strongly oblique, rounded, somewhat wider than 
high, the margins approaching. There is sometimes a very low, 
oblique callus pad or ‘‘tooth” on the parietal wall, further in and 
nearer the periphery than is usual in helices. This tooth is visible 
in all adult shells from station 281, but seems to be only occasional 
in other lots. It is present but excessively weak in the figured type, 
but is well developed in a paratype. 
The soft anatomy, examined in specimens from Stations 270, 
274 and 281, shows that this form is not nearly related to S. granu- 
latissima. The animal is plumbeous black above; sole with a wide 
isabella colored central area, sharply defined, and dusky side areas. 
Genital organs are relatively large. The penis is long with a short 
sheath, thin-walled, containing a long fleshy papilla having nu- 
merous slender longitudinal ridges, the end abruptly truncate. 
Penial retractor short, on the epiphallus, which is twisted around the 
retractor, the basal part thickened. No flagellum. The vagina is 
long. 
Matsenria Nod ch eee octane lene ack eee 44054 44037 
1 EXEL AUS BRC ROAM RR oe eta te ea Aer I fol st OO aM a oN 20 mm. ae 
Peis papilla s. < ae een cat cere ee «ere 1A Ge 12 
PODIUM AIS si eee Re eee aha: ee ay ae LD Pee , 
Penal vetrnctor. a hiic! nee Le ee ee 5 x 8 
WSR eS cc UE Sd awl ca 0) gee a Ce ae LG! a 
The peculiar sculpture of the penis-papilla is unique in the genus. 
The “tooth” on the parietal wall is a very unusual feature in 
Sonorella, but occurs also, and more strongly developed, in S. dalli. 
Sonorella insignis Pils. & Ferr. Plate II, fig. 3. 
Nautilus, vol. 33, July 1919, p. 21. 
Whetstone Mountains, Stations 304, 3042 and 305 (1919). Liv- 
ing specimens were taken only at the type Station 304. 
The shell is much depressed, openly umbilicate (the umbilicus 
about one-fifth the total diameter), solid, opaque, whitish stained 
with light pinkish-cinnamon above and in places on the base, 
banded with chestnut-brown, the band broad, situated well above 
the periphery. Surface with little gloss, having coarse, unevenly 
developed, very low plications in the direction of growth lines, and 
mainly confined to the last whorl; under the microscope traces of 
rather coarse, well separated spiral impressed lines may be deci- 
phered in some places on the upper surface. No _ protractive 
threads are visible on the embryonic shell in the adult or nearly 
adult shells. The last whorl descends rather deeply to the aperture, 
which is oval with converging margins, very slightly expanded. 
