SHIZOPOD^. 45 



of tlie little animals which compose it, and as these are 

 not placed irregularly, as in the larger species, but are 

 arranged in rings or whorls, it puts on a very beautiful 

 appearance, resembling a gem studded with the diamond 

 or opal, Plate 8, fig. 3. This species did not exceed an 

 inch in length, had about seven or eight rows of animals, 

 and a somewhat contracted aperture ; this species I would 

 designate by the specific appellation pygmcea. Subsequent 

 to the discovery of the Pyrosoma atlantica, two other 

 species of this very remarkable Genus have been detected 

 in the Mediterranean, viz. Pyrosoma elegans* resembling 

 my P. pygmeea, and Pyrosoma gigantea f having a 

 greater degree of afiinity with P. atlantica, but having the 

 mouths of many of the animals furnished with a foliaceous 

 appendage probably conducing to the locomotion of the ag- 

 gregate ; this species exceeds a foot in length. We have 

 yet to learn whether these species are luminous, but they 

 have furnished Naturalists with the means of becoming 

 acquainted with the very peculiar structure of Pyrosoma, 

 Avhich will be found amply developed by the authors above 

 cited. I cannot dismiss this subject without adverting to 

 a point connected with the economy of these animals 

 which seems to declare that the Atlantic species have been 

 created for the locality where we find them ; possessing no 

 power of locomotion in themselves, they are driven to and 

 fro by the light and variable winds which are known to pre- 

 vail to the north of the equator, and repressedfrom emigration 

 into either Temperate zone by the constant action of the 

 Trade winds on the North and South : the Mediterranean 

 species on the other hand, inhabiting a sea influenced by 

 tides, and by winds and currents altogether variable and 

 often rude, are furnished with exterior appendages which 



* Le Sueur, Nouv. Bull, des Sciences, Juin 1813, p. 283. pi. 5 fig. 2 ; and 

 Mai 1815, pi. 1, fig. 4. 



t Idem, Mai 1815, p. 80, pi. 1, fig. 1-3, 5-13. and Journ. de Phys. Juin 

 1815, fig. 1 -3, 5- 13. Savigny^Mem. sur les anim. sans Vcitebres, Memoir 3d 

 pi. 4. fig. 7. and pi. 22. 23. 



F 



