22 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 



row of small, thread-like, simple tentacles on both of the wide sides of 

 the mouth. The median tentacles, one on each side in the axial plane, 

 are longer than the others and are provided with simple, lateral fila- 

 ments. These are the primary tentacles of the larva which still persist 

 in the adult. The stomodasum is long and narrow, and the mouth is 

 a long cleft, perpendicular to the tentacular diameter. The funnel is 

 very short, being only about one-seventh as long as the stomodaeum. 

 The peripheral tubes of the gastro-vascular system are of small caliber. 

 The meridional ventral tubes give rise to very complex and variable 

 windings in the oral lobes. The entire animal is almost transparent, 

 but when mature is slightly milky in hue. 



The development has been studied by A. Agassiz. The general 

 appearance of the very young animal is quite similar to that of the 

 young Pleurohrachia or Mertensia. The 2 tentacles of the young larva 

 are long and flexible and are provided with numerous, simple lateral 

 filaments, as in Mertensia. The stomodaeum and the chymiferous tubes 

 are more slender in the young Bolinopsis than they are in Pleurohrachia. 

 As development proceeds, the general outline of the body becomes egg- 

 shaped, the aboral pole being blunt, and the tentacular diameter com- 

 pressed. The oral lobes appear quite late on both sides of the mouth 

 and still later the auricles begin to develop at the inner angles of the 

 bases of the lobes. At the same time the bases of the 2 tentacles begin 

 to migrate downward toward the sides of the mouth, carrying their 

 chymiferous tubes down with them. The meridional tubes are at first 

 simple and blindly ending as in Mertensia, and lie immediately under 

 the combs of cilia; but when the oral lobes begin to develop they extend 

 downward and finally form closed loops by the fusion of their free ends. 

 Thus the meridional ventral tubes of adjacent sides are joined through 

 complex windings in the oral lobes; while the meridional tentacular 

 tubes extend outward through the auricles and downward around the 

 free lower borders of the oral lobes. They also join with the oral forks 

 of the lower ends of the paragastric canals, thus forming a closed circuit 

 around the mouth. The details of the development are fully described 

 and illustrated by A. Agassiz, 1865, 1874. 



This is one of the commonest ctenophores along the New England 

 coast north of Cape Cod. It is not found on the southern coast of New 

 England, but is exceedingly abundant off the coast of Newfoundland, or 

 northern Maine in summer. It also occurs throughout the Arctic regions 

 and off the coasts of Norway and Scotland, and southward to the shores 

 of Northern Germany. I believe that Bolina septentrionalis of Mertens, 

 1833, is this same ctenophore from Behring Sea. 



Romer, 1903 (Fauna Arctica, p. 80), gives a detailed account of its 

 distribution and a long list of its synonyms. 



Bolinopsis vitrea. (Figs. 16 to 19, plate 5.) 



Bolina vitrea, Agassiz, L. i860. Cent. Nat. Hist. U. S., vol. 3, pp. 250, 269, 289, 

 fig- 93- — Agassiz, A., 1865, North Amer. Acalephae, p. 19, fig. 19. — Chun, 

 1898, Ctenophoren der Plankton-Expedition, p. 22. — Mayer, 1900, Bull. 

 Museum Comp. Zool. at Harvard College, vol. 37, p. 81, figs. 91, 92, plate 27. 



Bolina hydatina, Cnun, 1880, Ctenophoren des Golfes von Neapel, p. 292, Taf. 4, 

 fign. s, 6. 



