THE GENUS ANASPIDES. 795 



versally accepted association of Euphausiidse with Mysidse and their allies in 

 the group Schizopoda, it is manifest, then, from the leading characters enumerated 

 above, that Anaspides deserves to be also included in the Schizopoda, as it has 

 been by its discoverer. But while we are content to place it so, its admission vastly 

 increases the extent and importance of that group, for Anaspides stands far remote, 

 within the group's now extended boundaries. The precise rank which we are to assign 

 to it among the other members of the Schizopoda depends on the view we take as to 

 the relations of these to one another. The commonly accepted classification of Saes * 

 divides the sub-order Schizopoda into four families, Lophogastridse, Eucopiidse, Euphau- 

 siidse, and Mysidse, to which Mr Thomson has added a fifth, Anaspidse, for the recep- 

 tion of the genus under consideration. But the equivalence of these families is open to 

 doubt, and some authorities have even denied the natural character of the group Schizo- 

 poda itself. Boas t has proposed to break up the Schizopoda into two orders, Mysicl- 

 acea (including the Mysidse, Lophogastridse, and Eucopiidse of Saes) and Euphau- 

 siacea {Euphausiidse of Saes), which he regards as not more nearly related to each other 

 than they are respectively to the adjacent orders Isopoda and Decapoda. This dis- 

 memberment of the Schizopoda, which is also advocated by Hansen, \ and adopted by 

 Oetmann, § has not been generally followed, but it must, we think, be recognised that it 

 indicates the chief natural line of division among the organisms composing the group. 

 This is the view taken by Geestaeckee, |J who divides the Schizopoda into two tribes, 

 Holotropha and Hemitropha, corresponding respectively to the orders Mysidacea and 

 Euphausiacea of Boas. Taking, then, the Mysid and the Euphausid as the two great 

 types of Schizopoda, the points in which Anaspides approximates to one or other may 

 be summarised as follows : the presence of only two joints in the peduncle of the 

 antennse, the characters of the first maxilla, the comparatively slight differentiation of the 

 maxilliped from the rest of the thoracic limbs, the probable absence of a brood pouch, 

 the presence of well-developed swimmerets in both sexes, and the modification of the 

 first two pairs in the male, are all characters which incline towards the Euphausid type. 

 With the exception of the first and last, we may look upon all these as points in which 

 the Euphausid is more primitive and less differentiated than the Mysid type. On the 

 other hand, the characters of the mandible and of the second maxilla resemble the 

 Mysid rather than the Euphausid type, though not very closely comparable with either. 

 The number of joints and mode of flexure of the thoracic legs are those of the Mysidse, 

 and we may also recall in this connection the fact that the carapace, the want of which 

 is the most striking feature of Anaspides, is less strongly developed in the Mysidse, 

 where it leaves five of the thoracic segments free, than in the Euphausiidse, where it is 

 fused with all except the last. But besides the characters that permit us to acquiesce 

 in its status as a Schizopod, the singular interest attaching to Anaspides is not dimin- 

 ished, and the difficulty of comprehending it is much increased by the coincident presence 



* Challenger Rep., Schizopoda. f Morph. Jahrb., viii., 1882. % Zool. Anz., xvi., 1893, pp. 202-5. 



§ Plankton Exp., Decapoden u, Schizopoden. || Bronn's Klassen u. Ordn. d. Tliierreichs, Arthropoda. 



VOL. XXXVIII. PAET IV. (NO. 23). 5 T 



