CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 39 



canals, there are numerous wart-like protuberances, under which lie 

 diverticula of the canals. The lateral branches of the paragastric tubes 

 give rise to complex windings near the inner sides of the auricles, and 

 the meridional ventral tubes wind complexly in the oral lappets, forming 

 complete circuits. The stomodaeum is fiat and its broad side is con- 

 stricted near the middle. The axial funnel-tube is only about one- 

 eighth as long as the stomodaeum and the meridional canals are of fine 

 caliber. There are no tentacles and no tentacular vessels. The animal 

 is of a milky translucent hue, the wart -like protuberances on the oral 

 lobes being milky-white in color. 



Young animal: When the broad, lateral diameter is 8.5 mm. 

 (fig. 55, plate 10) the creature has assumed all the essential characters 

 of the adult except that the meridional ventral canals give rise to a simple 

 loop in the oral lobes and the lateral branches of the paragastric tubes 

 lead straight into the auricles and do not wind on the way, as in the 

 adult. There are neither tentacles nor tentacular canals. The auricles 

 are mere short, flat protuberances. The meridional ventral rows of 

 cilia consist of only 2 combs each, while the 4 auricular rows contain 3 

 combs each. The simple capsule of the apical sense-organ lies upon the 

 surface and is not sunken within a groove, as in the adult. A long, 

 narrow pole-plate extends out on both sides of the sense-organ. At this 

 stage the animal moves its oral lobes with great strength and agility 

 and swims with considerable rapidity. 



When the Ocyropsis is 26 mm. in its broad, lateral diameter (fig. 56, 

 plate 10) there are 11 to 12 combs of ciha in each subventral and the 

 same number in each auricular row. The lateral, bhnd branches of the 

 subventral canals in the lobes have appeared. The stomodaeum is 

 beginning to be constricted in the middle as in the adult, and the canal- 

 system begins to assume the characteristic windings. 



One often observes yellow or brownish-purple masses in the canals 

 of this ctenophore, especially in the blind side branches from the merid- 

 ional ventral vessels. These masses move about more or less in the 

 currents of the canal-system and disappear after the animal has been 

 captive, and unfed, in an aquarium for a day or two. I am inclined to 

 regard them as products of digestion or of excretion. 



This ctenophore is capricious in its appearance, but in some years 

 it is quite common at Tortugas, Florida, swimming in swarms near the 

 surface in spring and early summer on calm days, and sinking when the 

 sea becomes rippled. 



O. crystallina is widely distributed over the tropical Atlantic, and 

 it is represented in the tropical Pacific by a closely allied variety with 

 shorter auricles and longer oral lobes, which has recently been described 

 by Bigelow, 1904, as 0. ptercessa. 



Rang's Ocyropsis fusca is a imiformly light brownish or ocher- 

 colored form from the Cape Verde Islands. It has not been seen since 

 Rang described it in 1828. It is possible that this may be an O. crystallina 

 infested with commensal plant-cells, for such cells often infest the 

 ctenophores of warm or tropical oceans, although they are unknown 

 in species inhabiting cold seas. 



