PALEONTOLOGY. 401 



pear to have been very short, judging from the spherical cavities beneath 

 the anterior extremity of the carapace, which are small, close together 

 and shallow. ' 



The earliest form of decapod crustacean previously described, so far 

 as I can ascertain, is given by Mr.. Salter in the Quart. Jour. Geol. Soc. 

 London, vol. 17, p. 531, 1861, as Palegocran^on sociale; said to be from 

 the Lower Carboniferous limestone of Fifeshire, Scotland. There is 

 another supposed decapod, Gitocrangon, noticed by Richter (Beitrage 

 •Palseont. Thiring.) from the Upper Devonian, which is mentioned by 

 Salter; but of which he says he is doubtful if it be a crustacean at all. 

 I have not seen the work in which the original description occurs, and 

 can only judge of its nature from Mr. Salter's remarks. 



Palceopalcemon Newberryi. 



Pi,ate VIII, figs. 19-21.. 



PalcBopalemon Newberryi Whitfield, Am. Jour. Sci. and Arts, 3d series, vol. 19, 

 p. 41, 1880. 



Body slender, the carapace forming a little more than one-third of the entire 

 length, higher than wide, narrowed anteriorly and truncate behind; being longer 

 below than abovel; median line carinate, with a second carina on each side a little 

 below the crest; anterior end not rostrate but obliquely truncate, and sloping 

 rapidly backward above the truncation, forming when looked upon in front, a nar- 

 row elongated shield shaped and slightly depressed area, obtusely pointed above 

 and rapidly widening at the base, the lateral carin,e rising from the lower angles ; 

 lower posterior angles rounded, basal margins gently curved thoroughout and bor- 

 dered by a narrow thread-like band with a narrow groove within it. Abdomen 

 moderately robust, highly arched along the dorsal line, the pleura curving inward 

 below, giving a cj'lindrical form. Pleura broadly rounded at their extremities on 

 the anterior face, but slightly angular on the posterior corners ; posterior margin 

 of the segments strongly arching forward on the back. Telson elongate- triangular, 

 a little less than twice as long as wide, somewhat angular above and marked by a 

 central ridge below, and by a backward curving transverse ridge across the widest 

 part. Caudal flap large, forming a triangular plate on each side, the first and 

 second joints short, subtriangular ; marginal plate of the flap thickened, narrow, 

 and elongate, central plate narrowly triangular, a little longer than wide ; third or 

 inner plate of equal length with the second, and a little wider than the marginal 

 one ; the three combined as one, being apparently anchylosed at their margins to 

 form a solid piece. Antennae very strong, the first joint half as long as the thorax, 

 slightly swollen in their lower half, and flattened on the under side ; the other por- 

 tions unknown. Thoracic limbs very slender and only of moderate length, the 

 second joint laterally compressed, making the height nearly double the width; 

 other joints apparently cylindrical. Abdominal limbs known only by their second 

 (?) joints, which appear to be triangular in form, widening below, flattened and 

 plate-like in character or slightly convex on the anterior face. (In one case only 

 a single thread-like appendage can be seen as if projecting from the outer lower 



angle.) 



Surface of the carapace marked by very fine tortuous and interrupted, raised 

 lines, strongest anteriorly and running obliquely upward and backward; also by 

 a single, slender, distinct, raised ridge, extending more than one-fourth the length 

 of the carapace, orignating at the lower anterior angle, and passing upward and 



