46 



rounded. The amoiint of involution is very small indeed, and the inner 

 whorls are well exposed. They occupy a space about equal to one- 

 half of the entire diameter. The aperture is ovately orbicular, except 

 at the base which is very slightly emarginate ; its height and breadth 

 are nearly equal. 



The sculptm-e characteristic of the species is best seen in the last half 

 turn. It consists of transverse, raised lines, Avhich are found to be 

 minutel}'^ crenate when examined with a lens. They are jDlaced at 

 irregular intervals (of from one-sixth to one-eighth of an inch in width,) 

 upon the convex surface of the shell, and are not separated by any 

 corresponding grooves or depressions. Near the aperture there are a 

 few indistinct, but rather crowded revolving lines on the j^erij^hery and 

 outer half of the sides. A few faint ti-ansverse grooves, or constrictions, 

 (the remains of former lips) also cross the whorls at irregular but distant 

 intervals. Four of these can be counted on the last volution. 



The septa form three lobes on each side, of which the two outer ones 

 at least are very deeply and somewhat numerously divided ; the second 

 lateral lobe is placed on (or near) the umbilical border, and a single 

 accessory one on the inner margin of the whorls. The first and second 

 lateral lobes and saddles are bipartite with bifid subdivisions ; the dorsal 

 lobe is nearly as long as the first lateral, which is the broadest; the 

 siphonal saddle apj^ears to be elongate-conical, sinij)le and entire; it is 

 about one-half the height of the first lateral ; the outer branches of all 

 the saddles are scarcely longer than those of the inner ones. 



Greatest diameter, one inch and nine lines ; do. of the inner whorls,' nine 

 lines ; width of the outer whorl rather less than seven lines ; height of 

 the same, as measured from the outside, rather more than seven lines. 



As there is only one small specimen available for comp)arison, which 

 does not show the characters of the septation very clearly, it is doubtful 

 whether this shell should be regarded as identical with the Lytoceras 

 Liehigi of Oppel, or as a distinct species. So far as figures of the 

 European fossil enable one to judge, there are certaiulj^ some differences 

 between the two at the same age, but these are slight and, perhaps, 

 unimportant. In young shells of L. Liebi.gi, the amount of involution of 

 the whorls is greater than is the case with those of the Queen Charlotte 

 Island shell. The surfsice of the outer whorl of i. Liehigi is then marked 

 with three or four transverse raised ridges, which are so prominent as 

 to break the curve of its outline ; the few constrictions across the last 

 volution of L. crenocostatus are bounded by scarcely perceptible eleva- 

 tions. The latter is also rather the flattest of the two shells. Under all the 



