NATURAL SCIENCES OF PHILADELPHIA. 397 



its more numerous and greatly thicker interambulacral plates. The much 

 broader and more deeply sulcated arnbulacral areas of the two species now 

 known, also give them a peculiar melon-like form, quite unlike any of the 

 known species of Palcechinus. 



Melonites Dan^. Test large, subglobose, apparently slightly longer than 

 wide. Interambulacral areas lance-oval in form, convex, and occupied by 

 eight ranges of plates near the middle, where all, excepting those of the two 

 outer ranges are a little wider than high, and regularly hexagonal ; towards 

 the upp'-r and lower extremities of these spaces, the plates diminish in size 

 and numbers, and become proportionally higher, a few of them assuming a 

 pentagonal, or even a rhombic quadrangular outline. Those of the two lateral 

 ranges ail subpentagonal, their outer margins being somewhat rounded, 

 and more or less indented for the reception of the outer extremities of the 

 small arnbulacral pieces. Plates apparently all of uniform thickness, the 

 larger ones being about as thick as high, while the thickness of the smaller 

 grea'ly exceeds their diameter in any other direction. Arnbulacral areas 

 about half as wide as the interambulacral spaces, convex in the middle, and 

 broadly, as well as rather deeply sulcate along each side. Arnbulacral pieces 

 in four ranges, with some irregular intercalated smaller pieces between ; those 

 of the different ranges alternating, and all wider than high, as well as quite 

 irregular in form and size. Those composing the two inner ranges generally 

 four or five times as wide as high, but varying considerably in height. Usually 

 about four to five of the outer ranges, (which are of the same height, but only 

 half as wide as the inner, ) equal the height of each of the contiguous lateral 

 interambulacral plates. 



The intercalated pieces start from the zigzag suture between the two outer 

 ranges of arnbulacral pieces, and extend outward and inward between them, 

 but wedge out, or terminate abruptly, before reaching the outer margins, 

 or the middle of the arnbulacral areas. The pores are in pairs, two to each 

 piece, and arranged in four double rows, two on each side of the mesial 

 ridge or convexity of each ambulacrum. The entire surface is ornamented 

 by regularly disposed granules, about twenty to thirty-five of which may be 

 counted on each of the larger interambulacral plates, and as many, in propor- 

 tion to size, on each of the smaller ones, including the arnbulacral pieces. 



Height, 4 inches; breadth, about 3*80 inches ; breadth of one of the largest 

 interambulacral plates, 0'24 inch; height of do. 0"18 inch; thickening, 0-17 

 inch. 



This species attains about the same srze as, and very closely resembles, Melo- 

 nites multipora of Owen and Norwood, but may be at once distinguished by 

 having only four rows of ambrrlaeral pieces, and four double ranges of pores, 

 while M. multipora has uniformly double this number, both of pieces, and of 

 ranges of pores. 



We take great pleasure in dedicating this noble echinoid to Prof. James D. 

 Dana, of New Haven, Connecticut, one of the most profoundly learned of 

 living savans. 



Locality and position. Jersey county, near Warsaw, Illinois. Keokuk 

 division of the subcarboniferous series. 



Observations upon the Form of the Occiput in the various Racas of Men. 



BY J. AITKEN MEIGS, M. D. 



In 1S57, the collection of Human Crania in the Museum of the Academy of 

 Natural Sciences of Philadelphia, contained 1,045 specimens of many different 

 races of men. Since that time, by presentation, deposit and exchange, this total 

 has been increased to 1,125. Eighty additions, therefore, have been made 

 during the past three years. Of this number 27 are North American Indians ; 



I860.] 



