928 RECORD OF CURRENT RESEARCHES RELATraO TO 



a solely excretory function ; each of them consists of a branching 

 system of veins, giving off a number of finer vessels, which extend 

 to the periphery, but these do not appear to exhibit any regular 

 arrangement. 



In the Octopoda Dihranchiata we again find two renal sacs, which 

 communicate with the exterior by two ureters ; but the ureters are 

 papilliform. Veins traverse the sac, as in the Decapoda, and on their 

 course they also develop venous appendages (excretory organs) ; each 

 renal sac communicates with a system of canals which in the female 

 leads to the generative gland, and in the male to the investing sac. 

 In the female the canal-system is symmetrically developed, but in the 

 male, owing to the cxcentric position of the generative organs, it is 

 asymmetrical. The author's most important example in this group is 

 Octopus macropus. 



For the Tetrahranchiata the author had unfortunately to content 

 himself with a single example ; he was chiefly able to concern himself 

 with the venous apjiendages, and he finds that in histological struc- 

 ture they have a very close resemblance to the same organs in the 

 Dihranchiata, and the same is true as to the four renal sacs. 



If then the venous appendages of all the Cephalopoda are formed 

 on the same type it will be well to sum up their real characters ; they 

 are closed branching systems, arising from the veins, of a secretory 

 function ; this is shown not only by their structure and by their 

 relations to the veins but by the presence in their lumina of definite 

 bodies, which are obviously excretory products ; these last are always 

 given off in a solid condition ; and the fluid present appears to be 

 only the medium by which they are conveyed to the exterior. The 

 agreement between the Tetrahranchiata and Dihranchiata does not 

 end here ; in both, the pericardium is provided with slits, and though 

 those of the Decapoda do not now open into the pallial cavity, it is 

 very probable that they did so primarily. The branchial hearts do 

 indeed present rather more difiiculties, for in Nautilus the branchial 

 hearts with their appendages are not to be found in any viscero- 

 pericardiac cavity, but this may be explained by supposing that these 

 organs were in the Dihranchiata primitively separated off" from the 

 branchial arteries, and became locally developed to their present size. 

 In that artery it is possible to distinguish a longer and wider portion, 

 from one which is narrower and shorter; in the Dihranchiata these are 

 separated by the branchial heart, while in Nautilus the follicular 

 appendage is developed at their point of junction, and it was at this 

 point that the venous heart of the Dihranchiata was develojDed. If 

 this supposition be accepted, it easily follows that in all jn'obahility 

 the appendage of the venous heart was develojied from the follicular 

 appendage ; and there is still a great morphological similarity between 

 the two organs. 



The author is not inclined to agree with Hancock in regarding 

 the renal chamber of the Nudibrauchs as being homologous with the 

 renal chamber proper of the Cephalopod ; and he believes that the 

 English zoologist has been led astray by not taking into account the 

 organization of Nautilus ; nor does he seem to agree with the views 



