64 BULLEriN: museum of COMPAKATIYE ZOOLOGY. 



ness. It rests upon a mass of connective tissue (c.) much thicker than that form- 

 iu" the base of the larger organs, being in fact thicker than the leuticuhxr mass 

 itself. Above it is a similar layer of connective tissue (c^.) with thickly dis- 

 tributed nuclei very similar to that described above. The radiating fibrils 

 (J.) in this case seem to spring directly from the connective tissue itself with- 

 tjut anv intervening structureless mass. They are thicker, shorter, and more 

 closely packed than in the larger organs, and as they do not thin out toward.s 

 their extremities there is no clear zone produced on the outer surface. 



These smaller organs, too, appear to be much more brittle than the larger 

 ones, for only in very few cases have I found their sections at all complete. 



The only organs which at all approach the pallial organs just described are 

 to be found in tlie somewhat closely allied species Ahralla oiceni, which 

 ha-s been the subject of a memoir by Professor Joubin ('95). In common 

 with the form under consideration they are of a spheroidal shape and are 

 surrounded in their deeper half by sacs of pigment which may be modified 

 chroraatophores. The network of vessels described and figured by Jonbiu 

 (p. 11 [222], Fig. 6) appears to be replaced by the lacunae above mentioned. 

 Here, however, the resemblance ceases ; it is only with difficulty that the 

 internal structures can be regarded as in any way homologous with each 

 other. 



Judging by composition alone, it might be said that the crystalline style 

 (tige cristalline) of Joubin is represented by the funnel-like apparatus of 

 Ahraliopds, but even here differences obtain, for whilst the style occupies the 

 very centre of the organ, the funnel is hollow and in its middle is found a 

 cellular plug. Furthermore, the style is described as consisting of concentric 

 layers ami quite devoid of nuclei, whereas the funnel is made up of rodlike 

 elements, arranged around a centre, it is true, and nuclei, though in small 

 numbers, are present. 



There is nothing, apparently, in the organs of Abralia corresponding either 

 to the lens-like body, to the central cone, or to the hard posterior cup in 

 Ahmlinpsis, whilst on the otlier hand the latter shows nothing like the hood 

 (calotte) or the network (regean) observed in the former. 



In the face of discrepancies such as the.se in the case of forms which do not 

 seem to be far apart systematically, the elucidation of the functiotis of the dif- 

 ferent parts on anatomical or histological grounds seems wt-llnigli hopeless. 



I am not accpiainteil with any organs at all resembling those found on the 

 eyes of Abruliojms hoyhi. 



