with Modern Representatives. 395 



longer than the peduncle supporting them, the inner branch fringed 

 with spines. The largest specimen found measures 9 mm. in length. 



The foregoing six genera, comprising two living freshwater 

 forms, namely, Anaspides and Koonunga^ and four fossil forms, 

 namely, Prceanaspides, Gampsonyx, Acanthotelson, and Palceocaris, 

 notwithstanding various points of difference in details, seem, on 

 general grounds, entitled to be referred to Dr. Caiman's order 

 Anaspidacea. They all possess a small head (there is no extended 

 carapace). There is evidence that with the head the first thoracic 

 somite was usually coalesced. The eyes were generally pedunculated 

 (as in Anaspides),^ but in Koonunga they were sessile, and perhaps in 

 some fossil forms they may have been so also, or even wanting (?).- 



The antennules are generally large, with two flagella, supported on 

 a stout three- jointed peduncle. The antennae usually had three basal 

 joints, the third supporting a single flagellum and also an oval scale 

 (exopodite). 



Assuming the first thoracic segment to be coalesced with the head, 

 there remain seven free subequal segments each with a pair of 

 walking-legs (endopodites), of which the first was usually much the 

 longest and stoutest ; the four succeeding pairs each carried a setose 

 exopodite, and probably also two branchial laraellse on the basal joint, 

 as in the Schizopoda ; but the two hinder pair of legs seem to bave 

 been devoid of these appendages. The abdomen consisted of six free 

 subequal segments and a 'telson' or terminal joint; five of these 

 carried pairs of setose pleopods on stout basal joints. The sixth 

 segment (usually a little longer than the preceding, and more or less 

 cylindrical in form) bears the uropods, and to the centre of its posterior 

 margin is articulated the ' telson ' or terminal segment, which, with 

 the uropods of the preceding segment, forms the ' tail-fan.' 



Summing up on the question of the fossil genera, referred by 

 Dr. Packard to the Syncarida, namely, Palceocaris, Acanthotelson, and 

 Gampsonyx, Dr. Caiman writes (Trans. Hoy. Soc. Edinb., 1897, 

 vol. xxxviii (4), p. 801) : " We find, then, that Anaspides agrees with 

 the extinct genera above enumerated in the essential point in which 

 they have hitherto stood alone : the combination of Podophthalmate 

 characters with a completely segmented body, and the lack of a carapace. 

 We have seen that some at least, probably all, of these genera show 

 characters of the Schizopoda, to which group Anaspides is most closely 



1 Anaspides had also ocelli present on the cephalon ; we may therefore consider the 

 eyes in these primitive forms were affected by variable conditions, and we need not 

 necessarily split up the group on that account if the other characters tend to hold 

 them together. 



2 The genus Koonunga was not known when Dr. Caiman's paper was printed in 

 1897, nor has a figure of it yet been published (I have, however, been favoured by 

 being allowed to see an unpublished drawing). The absence of pedunculated eyes, etc., 

 has led its author, Mr. Sayce, to propose for it a separate family (the Koonungidfe, 

 under the order Anaspidacea) , but it seems desirable to await the fuller publication 

 and figure of this interesting crustacean before discussing its separation from the 

 other members of the o-roup. (See Mr. Sayce's preliminary paper, republished in 

 the Ann. and Mag. Nat. Hist., ser. viii, vol. i (April, 1908), pp. 350-5, with 

 Dr. Caiman's note thereon at the end.) 



