MAZATLAN UNIVALVES 399 
"17 by ‘07. It has a very broad, excavated infrasutural area, 
with a faint keel above, and one row of small tubercles below, 
shewing on the spire, and other smaller tubercular spiral hnes 
beneath. 
Hab.—Mazatlan ; 2 sp. off Chama and Spondylus ; L’pool Col. 
Tablet 1910 contains an imperfect operculum, which may 
belong to a large Drillia; of a rich, dark brown colour, rather 
undulated, with very faint marks of growth; inside with a 
large, nearly smooth scar bounded by a ridge. 
Tablet 1911 contains a very small operculum of somewhat 
concentric elements ; very thin; not unlike that of Clavatula 
bimarginata, figured in H. & A. Ad. Gen. vol. i. pl. 10, f. 5a. 
Genus CLATHURELLA.* 
Defrancia, Millet, Ann. Soe. Linn. Par. 1826.—Gray, Fig. 
Moll. An. p.73.—Phil, Handb. Conch. p. 137.—H. & A. Ad. 
Gen. vol. i. p. 95.—(Non Defrancia, Mill. Ind. Moll. Groent. 
p. 12,=Bela, Leach :—nee Defrancia, Bronn. 1825.) 
Clavatula, pars, Hinds.—The Lamarckian genus is restricted 
by Gray to the species which have a Purpuroid operculum. 
These shells are said to have none. 
471, CLATHURELLA RAVA, Hinds. 
Clavatula rava, Hinds, Proc. Zool. Soc. 1843, p. 39 :—Voy. 
Sulph. Moll. p. 17, no. 53, pl. 5, f. 18. 
Defrancia rana, H. & A. Ad. Gen. i. 96. 
?Non Pleurotoma rava, Rve. Conch. Ic. pl. 28, sp. 250. (Isl. 
Mindanao, Philippines, Cuming.) 
Two beautiful specimens were found, exactly agreeing with 
the accurate figure and description in the Voy. Sulph. Moll. 
As Reeve’s shell is from the Philippines, and differs in some 
particulars from this, it is probably a distinct species. Shell 
orange, with two purple brown bands; one in the infrasutural 
channel, which is ornamented with very fine undulated spiral 
striule ; the other continuing the suture round the base, and 
staining the inside of the aperture. Labrum and labium armed 
* This name is proposed for a convenient group of the Mangelia tribe; the 
name Defrancia, previously in use, being preoccupied, v. supra, p. 
