Ortmann — Crangopsis vermiformis. 287 



This fossil group of Crustaceans has become the more inter- 

 esting, since very recently a peculiar living species has been 

 discovered in fresh-water pools of the mountains of Tasmania, 

 which was first described by G. M. Thomson* under the generic 

 name of Anaspides, and of which W". T. Calmanf gives a 

 more detailed investigation, especially with reference to its 

 relation to the fossil forms here under discussion. Anaspides, 

 indeed, is the most important discovery among the recent 

 higher Crustaceans, and it is no doubt a living form belonging 

 to the group Syncarida. Caiman has shown conclusively that 

 the characters of Anaspides are a combination of the Podoph- 

 thalmate type (Thoracostraca) with a completely segmented 

 body and the lack of a carapace, i. e. with Edriophthalmate 

 type (Arthrostraca). But, on the other hand, the details of 

 structure in Anaspides point to a closer connection with the 

 V Schizopoda " of the Euphausid-type as well as of the Mysid- 

 type.J 



I think, however, it is best to regard the Syncarida of 

 Packard, including the recent genus Anaspides, as a group of 

 equal rank with the other chief divisions of the subclass Mala- 

 costraca, namely as an order, and, indeed, as the most primitive 

 order from which all the others are to be derived : there is no 

 doubt about the genetic relation of the Euphausiacea, Mysi- 

 dacea, and Decapoda to the Syncarida, but I am convinced 

 that further study will show that also the other orders of Mala- 

 costraca, Squillacea, Cumacea, Isopoda, and Amphipoda are to 

 be connected directly or indirectly with this primitive order. 



The chief characteristics of the order Syncarida (Packard") 

 derived from the morphological features displayed by the 

 recent Anaspides would be the following: 



Body with a limited number of distinct segments, differen- 

 tiated into a "cormus" and a "pleonP No carapace devel- 

 oped. Stalked eyes present. Antennas with a scale. Cormo- 

 pods on the coxal joints with "branchial lamellw," and on the 

 basal joints with an " exopodite" Penultimate segment of 

 the pleon with two well developed appendages forming with 

 the telson a caudal fin. 



Comparing Crangopsis with the Syncarida we see at once 

 that it is distinguished by the presence of a carapace, thus 

 coming clearly under the subdivision Thoracostraca. As we 

 have seen above, we may assign it to a particular order, Mysi- 

 dacea, but we must bear in mind that the typical characters of 

 this order drawn from the appendages of the body are not 



* Trans. Linn. Soc. Zool. (2), vol. vi, 1894. 



f Trans. Roy. Soc. Edinburgh, vol. xxxviii, part 4, 1896. 



X Compare Caiman, 1. c. p. 795 and 801. 



