19 



secm 1(1 be rare, each of thcm beinj^ represented by a single specimen only. It is a remarkable 

 fact, however, ihal the live specimens of Pcraclis were obtained from one single station, 

 otï Banda (Stat. 243). 



Limacina triacaiitJia ') (Fischer) is perhaps a species of Pcraclis too. 



Appendix to the Limacinidae. 



To the family Limacinidae some forms have been referred by several natiiralists, 

 which do not even belong to the Thecosomata. The "species" were based on minute shells, 

 which sometimes exhibited a right-handed spire. Most of these "new" forms, however, had 

 already disappeared, when Pelseneer began his task of criticizing the species of the "Pteropoda". 

 This author showed ") that species of the genus '^ Agadina' were only larvae of streptoneural 

 Gastropods, while at the same time he designated "'Limacina turritelloides' Boas ^), as a 

 young Ti'iforis. 



Having found among the spoils of the Siboga several sinistrorsal shells, evidently not 

 belonging to "Pteropods", I think it to be of some use to discuss them. 



I. "■Limacina iiirritalloides" Boas. 



1887. Limacina iiirritelloides Boas, Spolia atlantica, p. 49 — 50, Pi. III, fig. 35. 



1898. Simisigera tiirritclloides Oberwimmer, Denkschr. Kais. Akad. VVien, Bd. LXV, p. 592. 



Living animals: 



Stat. 148. o°i7'.6S., 129° 14'. 5 E. 4 spec. 



Stat. 222. 6° 10' S., 125° 35'. 5 E. 6 spec. 



It bas been with some doubt that Boas ^), who could only study the shell, has regarded 

 this form as a Limacina. With much authority however, this opinion was rejected by 

 Pelseneer ^), who also had only empty shells at his disposal. According to him this "■Limacina 

 turritelloides" was a young Triforis, identical with " Sinusigera perver sa'^ Graven ^j. Munthe"), 

 whose paper appeared only a few months before Pelseneer's work, maintained the species of 

 Boas as being a distinct form. 



The study of the animals themselves has shown me, that they are real larvae. I noticed 

 a broad foot and a four-lobed velum. The operculum, inserted to the posterior end of the 

 foot, has a large nucleus, the coils have a right-handed direction and increase slowly. 



The type on which the genus Agadina Gould ") has been based, was referred by 

 Pelseneer ") to Limacina antarctica, though Gould's figure exhibits a right-handed spiral. 

 Gould himself erected the genus " Agadijia' for his " Lhnacina cucullata\ 



i) Jouin. de Conch., vol. XXX, p. 49. 



2) Challenger Rep., LXV, p. 37 — 40. 



3) Spolia atlantica, p. 49 — 50, PI. 111, fig. 35. 



4) Op. cit. s. p. 40. 



5) Ann. Soc. Malacol. Belg., vol. XVIIl. p. 26. 



6) Pteropoder i Upsala Universitets Zoölogiska Museum, Bihang til K. Svenska Vet. Akad. Handlingar. Bd. 13, afd. IV, n" 2. 



7) U. S. Exploring Expedition under the commaud of Wilkes, 1852. Vol. XII, p. 486, PI. LI, figs óoirt, /». 



8) Challenger Report, L.W, p. 37. 



