XVII 
ON THE ANATOMY AND DEVELOPMENT OF 
PYROSOMA. 
Transactions of the Linnean Society of London, vol. xxtit., 1862, pp. 193-250. 
(Read December 1st, 1859.) 
§ 1. Hustory of the Genus PYROSOMA. 
THE genus Pyrosoma was first established in 1804 by Péron, in a 
memoir? published in the fourth volume of the ‘Annales du Muséum,’ 
and accompanied by a plate representing the exterior and a longitudinal 
section of the animal. Péron thus defines the genus and the species 
which he observed :— 
“ PYROSOMA. 
“ Corpus liberum, subconicum, extremitate ampliore apertum vacuum, 
aperturz margine intus tuberculis cincto. 
“PYROSOMA ATLANTICUM. /Equatorio-atlanticum, gregarie pelagi- 
vagum, viridissime phosphorescens, coloribus eximiis  tunc- 
effulgens, in aquis viginti duobus reaumurianis calidioribus 
occurrens, 10-12, I4-16 centrimetros zquans.” 
M. Péron’s conceptions of the exigencies of a zoological diagnosis 
were evidently of a singular kind, and his memoir contains not a 
single observation calculated to throw light upon the true nature of 
one of the most remarkable animals that has ever been discovered. 
1 « Mémoire sur Je nouveau genre Pyrosoma,” par M. Péron. Annales du Muséum, 
tom. iv. p. 437, 1804. 
Forskal’s Descriptiones Animalium (1775) contains the following passage :— 
‘¢29. MEDUSA BEROE. Tres ejus varietates vidi vel species. * * * * * 
“20, RUFESCENS : ovato-oblonga ; spe 5 poll. longa ; intus prorsus vacua. Gallicé, Con- 
combre de la mer. In mari Mediterraneo frequens.” 
Was Medusa Berée rufescens a Pyrosoma? 
