96 THE OCEANIC HYDROZOA.. 



developed into the clavate bodies and then fall off, either alone or in connexion with 

 one of the small suckers as 3'oung- buds." 



In 1847, during the voyage of H.M.S. 'Rattlesnake,' P sent from Australia to the 

 Linnean Society, a memoir on the structure of Plnjsalia, which was read before that learned 

 body on the 21st of November and the 5th of December, 1848, but the following abstract 

 from the 'Proceedings of the Linnean Society,' vol. ii, p. 3, 1855, is all that has appeared of 

 its contents. 



"The specimens of PJit/salia on which Mr. Huxley's observations were made, were 

 collected on board the ' Rattlesnake,' between the 25th of February and the 3d of March, 

 between lat. 25° and 37° south, and long. 5° and 7° west. They varied in size from one sixth 

 of an inch to two inches, in the long diameter of the float. The author first describes the 

 general appearance of the specimens, of which he doubts whether the largest were adult, 

 and then proceeds to a minute examination of their details, dividing them for this purpose 

 into the float, air-bladder, and the appendages, of greater or less length, which depend from 

 it, when the animal is in its natural position at the surface of the water. The smaller 

 specimens he states to be the best adapted for examination. 



"The float is described as consisting of an outer coat, an inner coat, and an air- sac, 

 contained within them, attached only to one spot of their parictes, and there communicating 

 with the exterior by a small constricted aperture, which was always found on the upper surface. 

 The disposition of the appendages is very irregular, but the larger tentacles are generally 

 placed more externally, the smaller and nascent organs more towards the centre. These 

 appendages are of three kinds, and consist of stomachal sacs, tentacles, and cyathiform bodies. 

 " Of each of these the author gives a detailed description, in their more perfect form, 

 as well as in their undeveloped state, as nascent organs ; and then proceeds to inquire, 

 first, what is the physiological importance of the organs described, and, secondly, what 

 zoological place should be occupied by an animal provided with such organs, so disposed. 



" Each of these questions the author treats at considerable length. Of the function of the 

 stomachal sacs in receiving the prey there can be little question ; but it may be doubted 

 whether the digested nutritive matter circulates in the ciliated water-carrying canals, 

 or is absorbed into totally different channels. 



"In the latter case, the purpose of the stomachal villi would plainly seem to be to absorb 

 nutritive matter, and convey it, through their central canal, to the wide interspace existing 

 between the outer and t!ie inner membrane ; but the author states that he has never 

 seen in this interspace any corpuscles analogous to those described by WilP as blood- 

 corpuscles. He suggests that the villosities noticed by Dr. Milne Edwards in the stomachal 

 sacs of Apolemia are the same organs, and not ovaries, as Dr. Milne Edwards considers them ; 

 and observes that similar organs exist in a Lijihjq {Etidoxia), hereafter to be more fully 

 described. 



" The functions of the tentacles, both as prehensile and defensive organs, admit of little 

 doubt, and on this subject the author notices an erroneous view of M. Lesson, who describes 



' By accident, the autlior of the communication is called 'WilUam' Huxley in the ' Proceedings.' 

 ^ I should stale that Will's ' Horse Tergestinse ' was one of my few books, and that for a long 

 time I made great efforts to see the vascular system which he has imagined to exist in many Hydrozoa. 



