84 LIFE OF PROFESSOR HUXLEY CHAP. V 



only specimens preserved in spirits. I have a great deal 

 to add and alter. Then as to Salpa, whose mode of 

 generation has always been so great a bone of contention, 

 I have a long series of observations and drawings which 

 I have verified over and over again, and which, if correct, 

 must give rise to quite a new view of the matter. I may 

 mention as an interesting fact that in these animals so 

 low in the scale I have found a placental circulation, 

 rudimentary indeed, but nevertheless a perfect model on 

 a small scale of that which takes place in the mammalia. 

 6. I have the materials for a monograph upon the 

 Acalephae and Hydrostatic Acalephse. I have examined 

 very carefully more than forty genera of these animals 

 many of them very rare, and some quite new. But I 

 paid comparatively little attention to the collection of 

 new species, caring rather to come to some clear and 

 definite idea as to the structure of those which had 

 indeed been long known, but very little understood. 

 Unfortunately for science, but fortunately for me, this 

 method appears to have been somewhat novel with 

 observers of these animals, and consequently everywhere 

 new and remarkable facts were to be had for the picking 

 up. 



It is not to be supposed that one could occupy one's 

 self with the animals for so long without coming to some 

 conclusion as to their systematic place, however sitbsidi- 

 ary to observation such considerations must always be 

 regarded, and it seems to me (although on such matters I 

 can of course only speak with the greatest hesitation) that 

 just as the more minute and careful observations made 

 upon the old " Vermes " of Linnaeus necessitated the 

 breaking up of that class into several very distinct classes, 

 so more careful investigation requires the breaking up of 

 Cuvier's " Radiata " (which succeeded the " Vermes " as a 

 sort of zoological lumber-room) into several very distinct 

 and well-defined new classes, of which the Acalephse, 

 Hydrostatic Acalephse, actinoid and hydroid polypes, will 



