CTENOPHORES. 



477 



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 towards 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 regards 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 Beroidce and their broods must be regarded as the principal 

 source of marine phosphoresence 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 Tnulticornis) sexually 

 mature larvas, or larva3 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 coloured 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 8 inches, and are 

 of a delicate red colour, which appears marbled. This appearance is due to the 

 branching of the eight principal canals above described, the ramifications forming 

 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 

 approaching 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 succeeded 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 annexed illustration, is so called because the 

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

 under edge of the ribbon half-way along it. This girdle-shaped, transparent 

 creature, iridescent in the sunshine, is a dazzling sight. The ribbon is edged with 



