204. BULLETIN OF THE 
Pleurotomella Agassizii Vrrrırı and SwrTH. 
VERRILL, Trans. Conn. Acad., V. p. 454, pl. 57, figs. 9, 9a; VI. p. 265, 1884. 
Darr, this Bulletin, XVIII. p. 121, 1889. 
Non Pleurotomella Sanderson, Dall, loc. cit. 
Pleurotomella Agassiziı Dall, Bulletin U. S. Nat. Mus., No. 37, p. 197, pl. 60, fig. 67, 
non figs. 71, 7la, 1889. 
Pleurotomella Agassizu var. mexicana Dall, this Bulletin, X VIII p. 121, 1889. 
* Mangilia Agassizii var. mexicana Dall, Bulletin U. S. Nat. Mus., No. 97, p. 180, 
pl. 11, fig. 14, 1889. 
Pleurotomella Agassizü var. permagna Dall, Proc. U. S. Nat. Mus., XII. p. 908, 1889. 
Two living specimens and one dead, Station 305, east of George's Bank, in 
810 fathoms. One dead, Station 325, off Cape Fear, N. C., in 647 fathoms. 
Three living (one young), Station 326, off Cape Fear, in 464 fathoms, One 
living and six dead (four young), Station 329, off Cape Lookout, N. C., in 603 
fathoms. Two dead, Station 330, north of Cape Hatteras, N. C., in 1,047 fath- 
oms. One living, Station 334, off Delaware Bay, in 395 fathoms. One living 
and two dead, Station 337, off Delaware Bay, in 740 fathoms. One living and 
one dead, Station 342, south of Martha’s Vineyard, in 1,002 fathoms. One 
living, Station 348, south of Martha’s Vineyard, in 732 fathoms. 
A common species found by the U.S. F., C. from east of George’s Bank 
to off Cape Hatteras, N. C., in 39 to 1,608 fathoms, not living below 1,539 
fathoms. 
Extending south as far as Tobago, in 202 to 880 fathoms (Dall), Living in 
841 fathoms. 
Mr. Dall gives the varietal name mexicana! to specimens of this species 
found in the Gulf of Mexico, on account of their being of small size, white, 
with faint color on the columella. In the hundreds of specimens from North- 
ern waters in the F. C. collection there is great variation in form, elegance of 
sculpture, and purity of color, To an elongated form he gives the varietal 
name of permagna. This is a quite common form among our specimens, 
although I have found none that reach a length of 47 mm. Their lengths 
range from 30 to 40 mm. 
We have the perfect young of this species in all stages of development from 
5 mm. on, and I have carefully compared them with a series of Plewrotomella 
Sanderson? Verrill,? but do not agree with Mr. Dall in combining the two spe- 
cies. The large, inflated body whorl, abruptly tapered spire, small nucleus, 
and the comparative smoothness of the surface, are characters which ought 
sufficiently to distinguish the young of P. Agassizii from the latter, which is 
slender, gradually tapered, with large nucleus, and very prominent though 
delicate sculpture. 
1 The figure quoted above was first published in this Bulletin, XVIII Dh 
fig. 14, as Mangilia ipara Dall, p. 115. Mr. Dall does not state whether the change 
was intentional or not. 
p 
? Trans. Conn. Acad., VI. pp. 149, 266, pl. 31, figs. 8, 3a, 1884 
