DALL: MOLLUSCA AND BRACHIOPODA. 239 
follow the extremists and reject such a name as Cylichna Lovén, on account of 
the prior existence of Cylichnus Burmeister, as has been pointed out by Pilsbry 
we must take the next valid group-name given to any part of the genus for the 
generic name and let subsequent appellations take precedence only in conformity 
with the order of their dates. 
Scaphander cylindrellus Datz1, n. sp. 
Plate 8, figure 1. 
Shell subcylindric, thin, white, covered with a pale straw-colored periostracum, 
the aperture as long as the shell, with one and a half visible whorls ; apex oc- 
cluded except the last whorl and a half, which rise above aud conspicuously over- 
hang the spiral excavated callous deposit, which is also deeply concave at its distal 
edge where it meets the aperture ; posterior margin raised above the edge of the 
preceding whorl in an even spiral, not produced at its termination as in most 
species of this genus; surface covered with minute spiral threads, mostly paired, 
the interspaces between the pairs usually wider than the threads and often wider 
than the pairs, the width decidedly irregular; the axial sculpture of small equal 
threads subequally spaced and crossing the spiral interspaces, but not overriding 
the spiral threads; the reticulum formed is rectangular and does not give the 
effect of punctation; aperture somewhat wider in front, but not flaring, as in most 
species of the genus; outer lip thin, body with a thin callus extending on to the 
pillar which is not gyrate and has no chink behind it ; axis not pervious; anterior 
and posterior parts of the aperture excavated. Lon. of shell, 33; max. diam., 
16 mm. 
U.S. S. “Albatross,” station 4672, 88 miles southwest of Palominos Light, 
Peru, in 2845 fathoms, infusorial ooze, bottom temperature 35°.2 F. U.S. N. Mus. 
110,563. 
This species is much thinner and even more cylindrical than 8. gracilis Watson, 
which is its nearest ally in the genus. 
Scaphander interruptus Datu. 
Plate 19, figure 9. 
Scaphander interruptus Dall, Proc. U. S. Nat. Mus., 1889, 12, p. 297, pl. 12, fig. 12. 
U.S. 8. “ Albatross,” station 2788, on the southern coast of Chile, in 1050 
fathoms, mud, bottom temperature 37° F.; station 2807, near the Galapagos 
Islands, in 812 fathoms, ooze, temperature 38°.4 ; station 3392, in the Pacific west 
of the Gulf of Panama and northwest of the Galapagos Islands, in 1270 fathoms, 
hard bottom, temperature at bottom 36°.4 F. U.S. N. Mus. 123,077. One of 
the specimens obtained was living. 
Fragments were also obtained at station 3360, in 1672 fathoms, sand, tempera- 
