46 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 



In the Pacific Cesium the lateral ends of the long body bear yellow 

 pigment, according to the figure by Mertens, 1833, ^^^ the description 

 and figure by Bigelow, 1904. This has not been observed in the Atlantic 

 or Mediterranean Cesium, but it occurs in the closely allied Folia from 

 Tortugas. The coloration may be due to the presence of commensal 

 plant-cells. 



Genus FOLIA (nom. nov.) 



Vexillum, preoccupied by Bolten for Mollusca in 1798. 



Vexillum, Fol, 1869, Anat. und Entwick. der Rippenquallen, Berlin, p. 6. — Chun, 

 1880, Ctenophoren des Golfes von Neapel, pp. 300, 302. 



GENERIC CHARACTERS. 



CestidcB with body elongated in the stomodaeal axis, as in Cestum, 

 but with the aboral narrow edge flat, not arched, as in Cestum. The 4 

 subtentacular meridional tubes do not bend outward and inward from 

 their points of origin from the 4 adradial vessels as in Cestum, but pro- 

 ceed straight outward along the middle of the broad sides of the animal. 



The type species and only known form is Folia parallela of the Medi- 

 terranean and tropical Atlantic. 



The genus is closely allied to Cestum, but is at once distinguished 

 by its straight, subtentacular canals, whereas those of Cestum curve where 

 they arise from the axial canal-system. 



Unfortunately we can not retain the generic name Vexillum, for 

 it was preoccupied for Mollusca by Bolten, 1798, in Catalogus Museum 

 Boltenanum, Pars Secunda, p. 138, and this name is accepted by Her- 

 mannsen, 1847, in Indicis generum malacoz., vol. 2. I therefore propose 

 the name Folia, in honor of Professor Fol, who discovered this cteno- 

 phore among the Canar\' Islands. 



Folia parallela. (Figs. 62 to 65, plates 13 and 14.) 



Vexillum parallelum, Fol, 1869, Anat. und Entwick. der Rippenquallen, Berlin, 

 p. 6, Taf. 2, Fign. 1-5. — Chun, 1880, Ctenophoren des Golfes von Neapel, 

 p. 303, Taf. II, Fign. 4-6, Taf. 13, Fign. 14-17; 1898, Ctenophoren der Plank- 

 ton-Expedition, p. 21. — MosER, 1908, Abhandl. Akad. Miinchen, Suppl. Bd. 

 I, Abhandl. 4, p. 15. 



This species is smaller than Cestum veneris, being only about 1 5 mm. 

 high and 150 mm. wide. The aboral edge is nearly flat, not arched as 

 in Cestum. The stomodaeum is shorter than in Cestum, being not half 

 as long as the height (oral-aboral axis) of the animal. Above all the 4 

 subtentacular meridional tubes proceed straight outward along the middle 

 of the broad sides of the animal from their points of origin at the ends of 

 the 4 rudimentary adradial canals to the edge of the outermost sides 

 of the animal, where they join the 4 sub ventral canals. The separation 

 between the subtentacular and subventral rows of combs is not so wide 

 as in Cestum, being hardly perceptible in some specimens. The tentacle- 

 bulb and its sheath are smaller than in Cestum. In the Mediterranean 

 the Folia is colorless, but at Tortugas, Florida, some of the specimens 

 (not all) show faint yellow in the gelatinous substance of the aboral 

 sides of the extended ends of the animal. This yellow color may, how- 

 ever, be due to the presence of commensal plant cells. Fol described 

 this ctenophore from the Canary Islands, and Chun found it in the Medi- 



