>\ 



T Mil-: sK<)t'.si!i;i!('. 



morphotogieni 



ue of the dif/ereni 



Is of ihf p'Kfl- 



\ timhf of ihr 



('riiflami. 



iil'f.. 



li\U ilia ihimiImt 111 Ca.si's, Imwcvcr. tin" nxl-sliapcd liiiiW a|i|iiMi\-> hi have (lr\ I'lujicd directly I'miii 

 tho foliaceous tvpo. As an instaiu-r cf this W . C.IKSl'.UKCll r iiiintioiis, 1913. p. 33, among other 

 thinjis. ..die stal>bt'inf6rnu<ron liinttMen Maxillfn uiid die iihtilieheii 'rhoiacnpodieii inatuher 

 () s t r a e o d e w" : for those form.s see below. 



1 1 seems, however, to he bv no means impossible that the developmont has sometimes 

 l.iMted.'d in tlie opposite direetion. that, for instance, more or less foliaceous limbs have been 



developed from biramou.s or rod-shaped limbs. Thus, 

 even if we accept the assmuption that the foliaceous 

 tvpe is the ptiinilive one in the Crustacea, we are not 

 by any means justified in assuming a priori that we 

 have an original type every time we meet this limb. 

 With regard to what might be called the 

 morphological value of the different parts of the 

 Crustacean post-oral limhs o])inions also still differ. 

 Thus E. KORSCHELT aixl K. HKlUKt;, in their work 

 of 1890, are of the opinion that the exopodite and 

 the (Midopodite are organs of equal value — they refer 

 them, as we have seen above, to the two main branches 

 of the Annelidan parapodium: when in a number of 

 forms, especially among the Malacosfraca, the endo- 

 podite forms a direct continuation of the protopodite, 

 while the exopodite appears in the form of a more or 

 less reduced appendage, this is — according to these 

 authors — not to be (considered as a primitive con- 

 dition; cf. loc. cit. p. 388. On the other hand, accor- 

 ding to these two authors the epipodial appendages 

 are of a different nature from the exopodite and endo- 

 podite; they are, as we see above, p. 22 homologized 

 with the dorsal cirri on the Annelidan p.arapodiuni. 

 J. Thiki.k protests against this view; in his 

 work of 1905, p. 466 he writes as follows: ,,Dazu be- 

 merke ich zunachst, dafi nach meiner Auffassung die 

 beiden Aste, Endopodit und Exopodit. urspriinglich durchaus nicht gleichwertig sind, sondern 

 der erst«re die einfache Fortsetzung des Stammes, der letztere ein Anhang desselben, dahei' 

 kann man sie nicht wohl auf die gegabelte Gestalt der Parapodien zuriickfiihren, s(mdern den 

 Basipoditen mit dem Endopoditen auf deren Stamm, den Exojjoditen auf einen dorsalen 

 Anhang, etwa einen Cirrus." 



Neither of these two alternatives can be said to be proved in anv way. So far both are 

 to be considered as assumptions. 



In my opinion there could o i- i g i n a 1 1 v scarcely have been 

 any essential morphological difference either between e x i t e s 



Fi;;. II. — Tin- ..sorontl thoracic fool" of Apiis 



cancrifonnis Sciiaff. 



iFr..in V.\\ Lankf-ster, 1881). 



