190 A DESCRIPTIVE CATALOGUE OF THE 
the mouth of which often are found young individuals of the same species. The 
Ianthinide differ chiefly from Scalide by the floating apparatus adapted to their 
oceanic life, Between the shells there are some marked transitions, e. g. Recluzia 
and the ribbed Ianthina (Iodina) exigua, Lam., on one side, and Scala (Lanthoscala) 
inconspicua, Sow., S. concinna, Sow., &c., on the other. The Scalide may be con- 
sidered creeping Ianthinide. 
Several attempts have been made to divide the genus Scala into subgenera, but 
as yet none have proved successful. In Cat. Yoldi, 1852, p. 48, I adopted the 
following divisions :— 
Acton, Leach, with the whorls separated. S. scalaris, L. 
Scaa, Klein (Clathrus, Oken), whorls not separated. 
Craturus, Gray (Scal. australis, Linn., and 8. grénlandica, Perry), with flat sutures. 
CrrsorreMA, Moreh, is generally adopted as a genus on account of the crispate varices. 
Actrsa, M6rch, Prod. Moll. Gronl. 1857; Adams’ Gen. Supp. Chiefly founded on the want of 
varices; this character is, however, very doubtful. Scala ochotensis, Midd., which evidently 
is nearly specifically the same, has sometimes rather distinct ribs, and Scala wroblewskyi, 
Morch (Scalaria borealis, Gould), is sometimes quite smooth. 
In the Genera of H. and A. Adams, Nov. 1853, p. 220, the following subgenera 
are added :— 
Ama@a, H. and A, Adams; Scala minuta, Bolt (Scala martinii, Wood.) 
The chief characters, rudimentary ribs and spiral striae, are not constant even 
in the same species. If the spiral line proves of generic value, Scala grénlandica 
would enter this genus chiefly, as Scala lovéni, Mac Andr., considered by several 
as a variety only, has spiniferous ribs like Amwa minuta. 
Opa.iA, H. and A. Adams, was established on species with a spiral basal ridge, 
a character probably of less importance, as Scala lamellosa, Lam., and Scala australis, 
Lam., scarcely can be congeneric. 
AcriLLa, H. and A, Adams, Proc. Zool. Soc. 1860, p. 241. Type Scala acumi- 
nata, Sowb. Shell turritelloid, ribs filiform. 
The geographical distribution of the Scalidz agrees in many respects with the 
Corals, the number of species being largest in the tropical seas, chiefly on the 
coral islands, and smallest towards the poles. 
Thus in the north polar region are only found four species: Scala grénlandica, 
Perry, is cireumpolar; in the sea of Greenland and Labrador is found besides this 
species Scala (Acirsa) borealis, Beck (Sc. eschrichtii, Holb.), which is not found 
recent on the European side of the Atlantic Ocean, but occurs fossil in Sweden 
(Uddevalla), Ireland, &c. 
In the northern part of the Pacific Ocean is found, besides Scala grénlandica, 
