40 GASTROPTERON. 



the head-disk, foot and wings are purple, orange-red or rose, more or 

 less maculated with whitish, head-disk and wings white-edged, sole 

 paler, and mantle with a posterior filament. 



G. pacificum Bergh, of the Aleutian Is., which is pale yellow 

 flecked with reddish throughout, the mantle with no filament or 

 flagellum behind, and 



G. sinense A. Ad., which has not yet been adequately described, 

 but seems nearest to G. rubrum. 



G. RUBRUM Rafinesque. PI. 7, figs. 1-10 ; pi. 8, figs. 11, 12, 13, 16. 



General color varying from red -purple to pale rose, sometimes 

 with some spots of bluish-white; on the periphery of the head-disk 

 and the parapodia there is an iridescent blue border. The ventral 

 surface of the foot proper is always paler in color than the rest of 

 the body. Mantle having a posterior filament. Jaws small. Rad- 

 ula with the formula 5'1'0'1'5. Shell nautiloid, microscopic, cal- 

 careous and very hyaline. 



Length, 20-24 ; breadth, 25-30 mill., or smaller. 



Mediterranean, JEgean and Adriatic Seas; Archachon basin, Gi- 

 ronde, 50-120 meters. 



Gastropteron KOSSE, De pteropodum ordine et novo 



ipsius genera, 1813, p. 10-16, figs. 11-14. Sar copter us ruber RAFIN- 

 ESQUE, Quadro dei generi di Moll. Pteropodi, in Specchio delle Sci., 

 ii, p. 11, Nov. 1814 ; Precis des decouvertes somiologiques ou Zool- 

 ogiques et Botaniques, p. 30 (1814). G. meckeli BLAINVILLE, 

 Manual de Mai. et Conch., p. 479 (1825). PHIL., Enum. Moll- 

 Sicil., i, p. 124. SOULEYET, Voy. Bonite, Zool., ii, p. 464, pi. 26. 

 KROHN, Archiv f. Naturg., 1860, p. 64, pi. 2, f. 2, 3 (larva and 

 shell). VAYSSIERE, Ann. Sc. Nat., Zool. (6) ix, p. 1-72, pi. 1-6 ; 

 Rech. Moll. Opistobr., Ire Pt., Tectibranches, p. 40, figs. 35-41. 

 BERGH, Zool. Jahrb., vii, p. 281-303, pi. 16, f. 1-27, pi. 17, f. 1-10- 

 Gastropteron rubrum FISCHER, Journ. de Conchyl., 1890, p. 349. 

 Gasteropteron coccineum FERUSSAC, Tabl. Syst. p. 25. Clioamati 

 DELLE CHIAJE, Mem. sulla Storia e Notomia degli Anim. senza 

 Vert, i, p. 53-59, pi. 2, f. 1-8 (1823). 



The shell-cavity of the mantle is very large, occupied throughout 

 its extent by a delicate, very hyaline membrane, at the posterior 

 part of which is found the small nautiloid shell (pi. 7, fig. 4). The 

 shell is nautiliform, hyaline and translucent, resembling in texture 



