416 



THE SPIKE-SHELL. 



representative species. The curious figure on the left-hand of the illustration is the 

 HVALEA, remarkable not only for the two wide fins which are found in all the family 

 to which it belongs, but for the long appendages which pass through certain aper- 

 tures in the shell, and trail behind as the creature proceeds on its course. It will be 

 also seen that the wings are united by a nearly semicircular lobe. The empty shell 

 is placed below in order to show its curious structure. 



JUST on the right of the Hyalea is a smaller creature, with an odd-looking three-pointed 

 shell, hanging as it were from the wings. * This is the CLEODORA, a very beautiful and 

 interesting animal, of which Mr. F. D. Bennett writes as follows : " On that part of the 

 body which is lodged in the apex of the shell, there is a small, globular, pellucid body, 





CAR1NARIA. Carlaaria Medlterranea. 

 HYALEA. Hyabea trideatata. (Empty shell below.) CYMBULIA. Cymbulla Peronll. 



CLEODORA. Cleodora pyramidata. SPIKE-SHELL. Cresels aclculata.. 



resembling a vesicle, and which at night emits a luminous gleam, sufficiently vivid to 

 be visible even when it is opposed to the strong light of a lamp. It is the only example 

 of a luminous shell-fish I have ever met with ; nor would the luminosity of this species 

 be of any avail, did not the shell possess a structure so vitreous and transparent. 

 Examples were chiefly captured at night or in the evening." 



AN allied genus, notable for the straight-pointed shell, is represented by the SPIKE- 

 SHELL, the little creature on the right of the Cleodora. The fins of this animal are 

 rather narrow, and the apex of the shell soon loses its sharpness, being by degrees 

 divided into compartments and gradually broken off. The Spike-shell is mostly found 

 near floating seaweed. 



