THE CTENOPHORES 3451 



ones. Ctenophores may continue to grow, if uninjured, almost indefinitely, or as 

 long as life lasts. Storms, however, destroy them. The largest specimens are, as a 

 rule, found in waters sheltered from the wind. They are to be seen throughout the 

 whole year, but are most plentiful during the spring months, and become rarer 

 toward summer, when some species, such as the Venus' girdle, almost completely 

 disappear. In the early autumn, however, great swarms appear, especially of Cestus 

 and Beroe. After a spring of active fertility, the larvae, at the beginning of the hot 

 months, sink down to greater depths, where they grow into adults, and come to the 

 surface again in swarms in autumn. 



Insignificant as these delicate creatures may appear, they delight the eye, both 

 while living and after death, by their luminosity. This is principally displayed in 

 the walls of the canals below the ribs. It is a curious fact, and one unique as re- 

 gards luminous marine animals, that Ctenophora, after being exposed for only a 

 short time to the light of the sun or the moon, or to artificial light, when suddenly 

 brought into a dark room, are incapable of giving light. Allman is of opinion that 

 the Beroidcz and their broods must be regarded as the principal source of marine 

 phosphorescence on the English coast. 



The Ctenophora are hermaphrodite; sexually mature animals of many species 

 being found throughout the whole year, while others occur only in spring, summer, 

 or winter. The young pass through a metamorphosis, or have larval stages which 

 precede the definite form. In at least one species (Eucharis multicornis) sexually 

 mature larvae, or larvae which are capable of reproduction as such, also occur; these, 

 when completely developed, become once more capable of reproduction as adults; 

 a method of multiplication which has been called dissogony. 



The most interesting, if not the most beautiful, of the Ctenophora are the 

 Beroidce, shown in the colored plate, which resemble Phrygian caps in shape. 

 In section, they are oval; the mouth is wide, and they have no capturing filaments 

 or tentacles, and therefore no adhesive cells. They attain a size of eight inches, 

 and are of a delicate red color, which appears marbled. This appearance is due to 

 the branching of the eight principal canals above described, the ramifications form- 

 ing a network. Beroe forskalia, shown in the plate, is found in the Mediterranean. 

 The Beroidce are carnivorous, feeding on their own relations of other genera. On 

 one occasion, a large Eucharis was placed in a basin with a Beroe forskalia, not half 

 its size, in a fasting condition. The latter, attracted by its wonted food, began 

 swimming round the Eucharis in large circles, with wide open mouth. On approch- 

 ing its victim, it darted at it, and seized it. The swimming plates of the Eucharis 

 beat helplessly, when, to the astonishment of the observers, this large creature was 

 completely mastered by the Beroe, which in less than a quarter of an hour suc- 

 ceeded in swallowing its victim, and, distended like a balloon, lay at the bottom 

 digesting it. 



The Cydippidce are conical, or barrel shaped, with the ribs uniformly developed, 

 and two opposite tentacles, one on each side. The beautiful creature figured in 

 the plate is Hormiphora plumosa from the Mediterranean. The remarkable 

 Venus' girdle (Cestus veneris), shown in the illustration, is so called because the 

 body is lengthened out sideways like a ribbon, so that the mouth is found on the 



