Notes on PhyUopodiform Crustaceans. 395 



EcHiNocAuis Wrightiana, Dawson, sp. Plate XIII. Figs, la, Ih. 



JSquisetides Wrightiana, Dawson, Quart. Journ. Geol. Soc. 1881, vol. xxxvii. p. 301, 

 pi. 12, fig. 10, and pi. 13, fig. 20. 



We have lately been favoured by Professor James Hall, of the 

 State Museum of Natural History, Albany, New York, with photo- 

 graphs, drawings, and casts of various Palgeozoic Crustaceans which 

 have of late come under liis notice. One of these, it appears to us, 

 should be referred to this categoiy of spiny -tailed Ceratiocarida. 

 It is only a fragment, consisting of no more than two abdominal 

 segments, but it represents a part of probably one of the finest 

 Phyllopod Crustaceans hitherto recorded. 



Fig. la represents the two segments seen in their narrowest (or 

 back) aspect, Fig. 16 being a portion of the lower segment of 

 Fig. la seen from the broader aspect (left side). The anterior, or 

 upper joint, overlaps the lower or under one, and at the junction 

 shows an inner crest. The ridges or folds, rise from the general 

 surface, and become stronger as they approach the posterior margin. 



The posterior border of the anterior segment is broken away, 

 showing the crust beneath. The posterior margin of the hinder 

 segment is better preserved, and shows the plications more nearly 

 entire. 



That these ridges or folds terminated in pointed spines which 

 overlapped the succeeding segment is clearly shown by the impres- 

 sions left by two of them upon the anterior (upper) edge, of the 

 lower segment (Fig. 16). 



Lastly, the peculiar pustulated and wrinkled surface of the 

 segments is such as we are accustomed to regard as crustacean, 

 resembling as it does the surface- markings observed by us on many 

 other Palaeozoic forms belonging to this class (see woodcut). 



I""''^ 



■'3 





'iii 1 





li 



'';:*iiii'^'ifliifii['!i»'')R 



.Kiilill 



A. Surface-markings of internal B. External surface -markings 



cast (magnified). (magnified). 



(Keproduced from sketches kindly supplied by Prof. James Hall.) 



"Without increasing therefore the number of genera, and indeed 

 being satisfied of its close relationship to the spiny forms above 

 mentioned, and described by Professor James Hall and Mr. R. P. 

 Whitfield respectively, we look upon the Devonian specimen in Mr. 

 Wright's Collection, " from the Portage Group (Upper Erian) of 

 Italy, New York," as Echinocaris Wrightiana, Dawson, sp.^ 



In size Echinocaris Wrightiana (Dawson) surpasses any specimen 

 of such Phyllopods that we know of. Its body-segments are not 

 compressed, and each is about 2 inches long, 2 inches high, and 



1 Mr. Whitfield and J. M. Clarke duly recognize this word as feminine, just as 

 Ceratiocaris, and all the names formed with xapis, ought to be regarded, although 

 often otherwise treated. 



