MACRTTROTTS DECAPOD IN THE LOWER CARBONIFEROUS. 5 / O 



orders limited to the Stomapoda and Decapoda. The same cha- 

 racter would indicate the latter of these as the proper resting-place 

 for the present form, whilst, from the number of ambulatory feet, 

 seven pairs, as I believe, there appears to be a transition towards the 

 Stomapoda. On the whole the Decapoda Macrura have perhaps the 

 strongest claim, especially when we take into consideration the well- 

 developed abdominal somites, the telson with its cau;lal appendages, 

 and the forwardly directed appendages. 



If we pass in review the thirteen genera enumerated in the 

 foregoing Bibliography, it is evident that some of them may be at 

 once eliminated as possessing little or no relation to th 3 present 

 form. Thus, referable to the Amphipoda are Dvplostylus, Salter, 

 Necrogammarus, H. Woodward, and Pala-ocrangon, Schauroth. The 

 first is represented by a few somites and a peculiarly distinctive 

 telson ; the second by three somites with the feet articulated along 

 the border, which Mr. Woodward attributed to a Crustacean allied 

 to the Gammaridoe of the Amphipods. The last, although approach- 

 ing nearest to our fossil, possesses sufficiently distinctive characters 

 to separate them. Passing to the Isopoda, we have Prcearcturus, 

 H. Woodw., Acanthotelson, Meek & Worthen, and Pedceocaris, M. 

 & W. The fragmentary remains referred to under the name of 

 Prcearcturus require, I think, no comparison with the present fossil. 

 In both the American genera the absence of a carapace, the division 

 of the somites into thoracic and abdominal, and the character of the 

 telson at once serve as points upon which to base a separation. 



Of the Stomapoda, we have Ampliipdtis, Salter ; Gampsonychus, 

 Burmeister; and ? Bostrichopus, (loldfuss. Again, in the case of 

 the last, I think, no comparison is necessary ; whilst in Amplii- 

 peltis the form of the carapace and number of the somites (9) pos- 

 terior to it will separate the two forms. As to Gampsonychus, the 

 somites are still further increased, and there is no coalescence into a 

 cephalothorax, although in the telson there is some resemblance. 

 We are now left with four genera, which have been referred by 

 their respective describers to the Decapoda: — Crangopsis, Salter ; 

 Gitocrangon, Richter ; Pygocephalus, Huxley; and Anthrapalcemon, 

 Salter ; and with these a more minute comparison is necessary. 



First, in Crangopsis the carapace is short and pointed ; here 

 it is oblong and broad ; the telson is small ; in our specimen it 

 is large ; the caudal appendages are obovate ; here, however, 

 they are broad, and apparently double on each side. Secondly, 

 in Gitocrangon the carapace is transversely segmented, the somites 

 are seven, and the telson is inconspicuous ; still it would be well if 

 a more satisfactory comparison with this genus could be made ; un- 

 fortunately little appears to have been written about it. Thirdly, 

 with regard to Pygocepludus, we fail to notice any separation into 

 the semicircular and quadrate disks of this genus in the present 

 fossil, although there appears to be a closer relationship with 

 P. Huxley i, H. Woodw., than with P. Cooperi, Huxley. 



Lastly, we have for consideration the genus Anthrapalozmon, of 

 which, I believe, our fossil is a species. In this genus the carapace 



