Ill -ON THE ANTHRACARIDil, A FAMILY OF CARBONIFEROUS MACRU- 



ROUS DECAPOD CRUSTACEA. 



SEAB APRIL 21, 1885. 



By A. S. Packard. 



Having been kindly favored by Messrs. R. D. Lacoe and J. C. Carr with the opportunity of 

 examining their collections of nodules from Mazon Creek containing Anthrapala'mon gracilis Meek 

 and Worthen, I Iiave been able to discover some features probably not shown in the 8j)ecimens 

 examined by Messrs. Meek and Worthen. The newly observed cliaracters are the Ciirapace with 

 its rostrnm, showing that the American species in these respects closely resembles the European 

 ones figured by Salter, the founder of the genus. Moreover, our specimens prove the existence of 

 five pairs of thoracic legs, while the antennae of both pairs are almost entirely shown. The fact 

 that the first pair of thoracic feet were scaicelj' larger than the succeeding pairs, suggests that 

 Anthrapalsemon cannot be pbiced in the Eryouidae, but shouhl form the type of a distinct group of 

 family rank, none of the existing Macrura, so far as we are aware, having sui'-h small anterior 

 legs. Other characteristics which we ahall point out confirm this view. 



The genus Anthrapalremon, a Carboniferous fossil, was first described by J. W. Salter in the 

 Quarterly Journal of the Geological Society of London (xvii, 529, 18(il). The name given to tbe 

 fossils has, the author remarks, "only a general signification, and is not intended to indicate a 

 real relation to Palsemon." He also i-emarks that " the genus is not to be confounded with any of 

 the Liassic or Oolitic ones jjublished by von Meyir, Miinster, &c. . . . It is broader than the 

 general form of the Astacida3,or than Glyphcea and its Liassic allies, but much narrower than IJryon." 

 Salter's type-species is Anthrapakemon grossarti Salter.* With this species the American A. 

 gracilis is congeneric. A closely allied English form, A. duhius Prestwich, is referred by Mr. Salter 

 to the subgenus raUcocarabus, a name even less fitting than Anthrapala-mon. Concerning the 

 other form provisionally referred to Authrapalemon by Mr. Salter (his Fig. 5), we will remark 

 In a supplementary note to this article. 



The only American species we have seent is Anthrapakemon gracilis Meek & Worthen, first 

 described in the Proceedings of the Academy of Natural Sciences of Philadelphia, 1865, and 

 redescribed and figured in the second volume of the Geological Survey of Illinois, and again in 

 the third volume. 



Mr. Salter figured the carapace and rostrum, as well as the abdomen of the Eurojiean species ; 

 while the specimen figured by Meek and Worthen evidently did not possess the carapace, but 

 showed perfectly the telsou and neighboring pair of abdominal appendages. 



The specimens loaned us by Mr. Lacoe enable us to give a more perfect description and illus- 

 trations of this important type ; and I am indebted to Dr. J. S. Kingsley lor the restoration and 



* In his Handbuch der Palicontologie, Zittel mentionH Pseudogalathea Peach, from the carbouiferous of Scotland. 

 We have not yet seen Mr. Peach's article. 



tDr. J. W. Dawsou has described and figured, the carapace of AiithrapaJwmon hiUianum, from the Carboniferous 

 of Nova Scotia. Geol. Mag., iv, new ser., p. 56, fig. 1, 1877. Also figured in his Acadian Geology, 1878. 



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