MORPHOLOGY OF BATHYNELLA AND ALLIED CRUSTACEA. 511 
I am still of opinion, for the reasons given above, that the 
freedom of the first thoracic somite is the most weighty mor- 
phological distinction between Bathynella and the other 
living Syncarida, and that it constitutes an important link 
between that genus and the fossil Ur one ctes and Palaeo- 
caris ; but so long as this evidence of affinity remains 
unsupported by other characters I am doubtful as to the 
desirability of establishing a new sub-order for these three 
genera. It seems better to be content with a division of the 
Syncarida (or Anaspidacea) directly into families, following 
in this the example of Geoffrey Smith, although both the 
definitions and the contents of the families recognised by him 
require modification. Several of the fossil genera, such as 
Nectotelson, Palasor chestia, and Gasocaris, are so 
imperfectly known that it is impossible to be sure of their 
place in any system. Pr aeanaspides, included by Geoffrey 
Smith in the family Anaspididae, has proved (Caiman, 1911) 
to be identical with Palaeocaris which he placed in the 
Gampsonychidas, although evidently suspecting that the two 
genera might be more closely related. With some changes 
in nomenclature recently made by Cockerell, the classification 
now stands as follows : 
Division Syncarida, Packard, 1885. 
Order Anaspidacea, Caiman, 1904. 
Family Anaspididae (Anaspidae, Thomson, 1893). 
Genera Anaspides, Thomson ; Paranaspides,, 
G. Smith. 
Family Koonungidae, Sayce, 1907. 
Genus Koonunga, Sayce. 
Family Acanthotelsonidae, Cockerell, 1916 
(= Pleurocaridae, Chappuis, 1915). 
Genera Acanthot el son , Meek and Worthen ; 
Pleurocaris, Caiman. 
Family Bathynellidae, Grobben, 1904. 
Genus Bathynella, Vejdovsky. 
Family Uronectidae, Cockerell, 1916 (= Gamps- 
onychidas, Packard, 1885). 
