468 GASTKOPODA. [Pectinibranchia. 



The last whorl occupies the whole height of the shell ; it is lightly 

 convex, narrowed below, with a light basal lirnb. Aperture high and 

 narrow, arched, narrowly rounded above, slightly emarginate below. 

 Outer lip convex, thickened, with a light varix, extending above be- 

 yond the spire and concealing it, inside lightly crenate. Columella 

 oblique, straight, with 4 almost transverse plaits, the lower two 

 stronger than the others. 



Diameter, 3-8 mm. ; height, 5-8 mm. 



Animal unknown. 



Type in the Canterbury Museum. Christchurch. 



Halt. Off south-east of Cape Saunders, in 100 fathoms (E. R. 

 Write). 



Tribe 2. TOXOGLOSSA. 



Stenoglossa without jaws; the radula normal, formula 1 + 0+1. 

 but exceptionally a central tooth is present, and sometimes an addi- 

 tional lateral tooth on each side, the formula being 1 1+ 1 + 1 1. 

 A " poison-gland " is present, whose duct traverses the nerve-collar. 

 The digestive tube is very narrow. The branchiae number two, and 

 are unequal. The siphon is long, slit longitudinally. The male 

 organ is well developed, and situated on the right side of the body. 



The animal is carnivorous, and exclusively marine. 



Fam. TURRITID^, H. and A. Adams. 

 Pleurotomatidce, Loven. 



Animal with widely separated tentacles, the eyes usually at or 

 near their base ; mantle generally with a sinus at the right margin 

 corresponding with the sinus of the shell ; siphon long. Dentition : 

 Usually there is no central tooth, and the laterals are a single one on 

 either side of the lingual band ; but in some groups there is a central 

 tooth, and in others there are 2 laterals. No jaws. The teeth are 

 long, usually subulate, supplied with venom from a large gland. 



Shell fusiform, with a more or less produced anterior canal, and a 

 slit or sinus on the outer margin of the aperture near the suture. 

 Operculimi (not always present) corneous, annular, the nucleus apical, 

 or subcentral and nearly marginal. 



In no other group of molluscs is it so difficult to -make a satisfac- 

 tory classification as in the Turritidce. The forms are exceedingly 

 numerous, and known in many species to be very variable in their 

 characters, whilst the material for the recognition of most of those 

 described is generally scanty. Living specimens are found in all seas. 



The family as a whole is not of very great antiquity, its main 

 features having been carved out in the Eocene, whilst many of its 

 broad characteristics were not evolved until the Miocene or early 

 Pliocene. 



Subfam. 1. TURRITIX.E. 



Operculum oval, with terminal nucleus. 



