THE GENUS ANASPIDES. 799 



From the region of the first or second segment behind the head there springs a stout 

 limb which reaches beyond the peduncle of the antennules. Four joints are visible, and 

 the last two are armed with stout spines which, on the last joint, seem to form a sort of 

 pseudo-chela. Packard identifies this limb as a mandibular palp, which he compares 

 with the enormously developed palp of Petalophthalmus. Apart from the fact that the 

 mandibular palp of the Malacostraca never presents more than three joints, the base of 

 this limb appears to be placed much too far back to correspond with the position of the 

 mandible, and it is more probable that it represents the first or second thoracic leg. 

 With reference to the other thoracic legs, Packard says that these, " irrespective of the 

 endopodites, are represented as biramous, and the two rami are drawn as of nearly equal 

 length. It is probable that there has been a mistake in drawing the legs, as in none of 

 the existing Schizopods, such as My sis and its allies Euphausia, Gnathophausia, Petaloph- 

 thalmus or Chalaraspis, are the legs thus thrice divided." In the preliminary note the 

 same passage occurs, but " breeding lamellae " is substituted for " endopodites," which 

 makes the last sentence still more obscure. As a matter of fact, the legs are shown in 

 Jordan and v. Meyer's figure as bifurcating near the tip, in the region, apparently, of 

 about the third last joint. This appearance is doubtless due, however, to the overlapping 

 of the appendages of the two sides. A confused mass which covers the bases of the legs 

 shows traces of what may have been exopodites, and may possibly involve also the 

 remains of gills. # The abdomen carries well-developed swimmerets. The tail-fan is 

 similar to that of Palseocaris ; the outer plates are divided by a suture, and the telson 

 is comparatively short and rounded. It is stated that the telson appears to be fused 

 with the last segment of the abdomen. If this be so, the tail-fan will bear some 

 resemblance to that of certain Isopoda, particularly of the Gnathiidw. 



Gampsonyx, then, while agreeing in general characters with Palseocaris, differs from 

 it in two points. It possesses an apparently free first thoracic segment only obscurely 

 indicated, if at all, in Palseocaris, and it has a pair of powerful raptorial limbs identified 

 by Packard as mandibular palps, but more probably to be referred to the first or second 

 thoracic limbs. Neither of these differences increase the resemblance with Anaspides, 

 unless indeed the " first thoracic " segments of the two are homologous, which is very 

 doubtful. The character of the limbs indicates that Gampsonyx is probably a some- 

 what more specialised development from the common stock to which both Anaspides 

 and Palseocaris are related. 



A CANTHOTELSON. 



Acanthotelson was described in 1860 by Meek and Worthen from the Coal Measures 

 of Illinois. It was doubtfully referred to the Isopoda by these authors, who, however, 

 noted its resemblances to the Decapoda. Packard has given a restoration (Plate II. 



* " Ueberdiess erkeimt man dass an der Wurzel der vordern sieben oder acht Fiisse noch besondere Anhangsel 

 vorhanden waren, und zwar von namhafter Liinge und Starke." — Jordan and v. Meyer, op. cit. 



