208 Linnaan Society. 



and long. 5° and 7° W. They varied in size from ^ in. to 2 in. 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 de- 

 tails, dividing them for this purpose into the float or 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 parietes, 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 ten- 

 tacles 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 import- 

 ance of the organs described, and secondly, what zoological place 

 should be occupied by an animal provided with such organs so dis- 

 posed. 



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 nu- 

 tritive matter circulates in the ciliated water-carrying canals or is 

 absorbed into totally diflferent channels. In the latter case the pur- 

 pose of the stomachal villi would plainly seem to be to absorb nutri- 

 tive matter and convey it through their central canal to the wide in- 

 terspace existing between the outer and inner membrane ; but the 

 author states that he has never seen in this interspace any corpuscles 

 analogous to those described by Will as blood-corpuscles. He sug- 

 gests that the villosities noticed by Dr. Milne-Edwards in the sto- 

 machal sacs of Apolemia are the same organs, and not ovaries as Dr. 

 Milne-Edwards considers them ; and observes that similar organs 

 exist in a Diphya {Eudoxia), hereafter to be more fully described. 

 The function of the tentacles, both as prehensile and defensive 

 organs, admits of little doubt ; and on thi* subject the author notices 

 an erroneous view of M. Lesson, who describes them merely as 

 ducts for conveying an (hypothetical) acrid fluid from an (hypotheti- 

 cal) poison-gland. He also controverts M. Lesson's opinion that cer- 

 tain of the colourless tentacles are to be regarded as branchiae ; being 

 quite convinced that there is no diff"erence between these and the 

 ordinary tentacles except in the absence of colour. As regards the 

 function of the cyathiform bodies, he has no other than analogical 

 evidence to offer. The only organs in the Acalephce with which he 

 conceives them to have any resemblance are the natatorial organs of 

 the Physophorce. But their little adaptation to a similar purpose, and 

 the entire absence even of their rudiments in young Physali^, dis- 

 courage this comparison ; while on the other hand they bear a sin- 



