354 GASTROPODA. [Pectinibranchia 



Diameter and height, 6^ mm. ; length, 12J mm. (type). 



Animal figured by Quoy and Gaimard. 



Type in the Mus. Hist. Nat., Paris. 



Hab. Tasman Sea, between Australia and New Zealand ; type 

 (Q. & G.). Mr. Hedley fixes the locality at about 158 E. longitude 

 and 40 S. latitude. This is nearly half-way between Bass and Cook 

 Straits, but somewhat nearer the former. 



Remark. It is not impossible that this rare mollusc inhabits 

 New Zealand waters, and may be obtained some day with the surface- 

 net. 



Fam. PTEROTRACHEIDJE, Gray. 



Animal having the visceral sac very much reduced, without shell 

 and mantle ; anus on the posterior part of the body ; foot provided 

 with a sucker in the male only. 



Genus 1. PTEROTRACHEA, Forskal, 1775. 



Pterotrachea, Forskal, Descript. Anim., 1775, 117. Type : P. coronata, 

 Forskal. Firola, Bruguiere, 1791. Hypterv.s, Rafinesque. 



Animal elongated, fusiform ; head proboscidiform, without ten- 

 tacles ; foot contracted at its base ; body carinated posteriorly, with 

 a filiform appendage, considered to have the function of a caudal fin. 

 Nucleus not terminal, covered by tegument, leaving only the posterior 

 part open. Branchise numerous, triangular, arranged around the 

 nucleus. Female genital orifice on the right side of the nucleus, near 

 the middle ; orifice of the male organ on the right side of the body, 

 between nucleus and ventral fin. 



Distribution. Atlantic, Mediterranean, Pacific. 



The embryos of Pterotrachea are protected by an operculate shell, 

 spiral, but the second whorl disconnected, a character which ap- 

 proaches them to the fossil genus Cyrtolithes. (Fischer.) 



These molluscs occur sometimes in great abundance, and Peron 

 and Lesueur said that, of all the animals the Mediterranean was 

 nourishing, there was perhaps no other genus more abundant than 

 Pterotrachea ; it is by thousands that one sees them floating at the 

 surface of the sea in calm weather, or thrown up on the beach after 

 gales, and sometimes they are brought up in the same abundance in 

 the nets of the fishermen. 



1. Pterotrachea coronata, Forskal, 1775. Plate 17, fig. 21. 



Pterotrachea coronala, Forskal, Descript. Anim., 1775, 117. E. A. Smith, 

 ('hall. Hep., xxiii, 12. Firola coron ata, Forskal : Cuvier, Regne Anim., 

 t>d. 2, iii, 09 ; Vayssiere, MolL Heterop. provenant des campagnes des 

 yachts " Hirontlelic " et " Princesse Alice," 1904, 33, pi. 3, f. 33-41 : 

 Benham, T.N.Z.I., xxxviii, 245, pi. 40, f. 1-3. Biphore elephantin, 

 Bory de St. Vincent. Pterotrachea umbilicata, Delle Chiaje. Firola 

 Edwardsiana, Deshayes. Hypterns erythrogaster, Ratinesque. 



