1882.] ‘LIGHTNING’ AND ‘ PORCUPINE” EXPEDITIONS. 661 
shaped, or conical with a triangular lobe on each side; these lobes 
seem to serve as flaps or wings to aid the locomotion of the animal, 
and are expanded or contracted accordingly : captacula very nume- 
rous (apparently from 50 to 100), cylindrical, slender, and extensile, 
each terminating in an oblong bulb: mantle forming a slight collar 
inside the mouth or front opening of the shell: gids or branchiz 
brown, arranged in two leaves: iver yellow, granular; the lower 
fourth of the shell is empty and not occupied by the animal. The 
captacula are always in active and incessant motion, even when 
the other parts of the animal are at rest. The action of the foot is 
somewhat like that of Crenell/a or Modiolaria. 
I admit that my friend Dr. Fischer is right in giving this species 
the name imposed by Sowerby, although I do not agree with the 
latter in saying that Mr. M*Andrew’s shell is the same as that from 
the Philippines. The latter species is larger and proportionally 
broader towards the front or anterior end, and is consequently less 
slender and thread-like; and it is also more curved. I would 
suggest for that species the name subrectum. 
I described the present species in the Ann. & Mag. N. H. for 
July 1870, as D. gracile ; but that name had been preoccupied by 
Prof. Meek for a North-American fossil. 
The colour of the shell is clear white; Sowerby described it as 
‘*pallide fulva.”’ There is a terminal sheath as in D. rubescens. 
My largest specimen is half an inch in length. It is more regularly 
cylindrical than the young of D. rubescens, narrower and nearly 
equal in breadth throughout. Very young specimens of the present 
species have a bulbous point like D. entalis and other species. 
1. SrpHopENTALIUM TERES’, Jeffreys. (Plate XLIX. fig. 5.) 
SHELL cylindrical, gradually tapering to the basal point or pos- 
terior extremity, gently curved, thin, glossy, and semitransparent ; 
sculpture, none except fine and numerous lines of growth: colour 
whitish : mouth circular: dase slightly but distinctly notched above 
and below. L. 0°35, B. 0°05. 
‘ Porcupine’ Exp. 1870, Atl. St. 16,17, 17a. 
The position of the terminal notches in this species differs from 
that of the slits in Dischides, being placed one on the convex and 
the other on the concave end of the shell in S. teres, instead of being 
bilateral as in that shell. 
yp PA 2. SIPHODENTALIUM AFFINE, M. Sars. 
Siphonodentalium affine, M. Sars, Christ. Vid. Selsk. Forh. 1864, 
p- 299, t. vi. #34, 35. 
‘ Porcupine’ Exp. 1869: St. 19, 28, 30. 1870: Atl. 3, 16, 
17, 17a. 
Distribution. Loffoden I., 100-300 fms. (M. Sars). ‘ Valorous’ 
Exp., 1450 fms. Nova Scotia, 35 fms. (Verrill)? 
Not the young of S. vitreum (see B. C. v. p. 196), which in all 
states of growth is more conical and not so cylindrical as S. affine ; 
and the base or point is also different. The present species is not 
half the size of S. ¢eres, and is much less slender and tapering. 
? Slender. 
