94 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



side of these extremes. They are about half as long as the median 

 furrow spines, flattened and subtruncate proximally (especially on 

 the inner part of plate), becoming terete and blunt clistally. The 

 spinelets are about the size of those of the actinal intermediate plates, 

 and do not form regular series, although sometimes an indistinct 

 arrangement in 2 longitudinal series is observable. As in A. ludwigi, 

 there are no enlarged subambulacral spines, but on the aboral side 

 of most of the plates is a conspicuous fasciculate pedicellaria, with 



6 to 8 papilliform, subtruncate, blunt, or pointed jaws, forming a 

 subcircular group surrounding a depression in the plate. On the 

 outer part of the ray numerous plates lack the pedicellaria. Prox- 

 imally some of the spinelets constituting the pedicellaria are broad- 

 ened and grooved at the tip. The form of the spinelets is rather 

 variable, however, some being tapered and bluntly pointed. In the 

 3 specimens of C luchoh/i which I have examined, the largest with 

 R, 103 mm., the subambulacral pedicellariae are similar to those of 

 G. astropectinides , except that the spinelets are a little more uni- 

 formly slender and pointed. The first plate is very strongly com- 

 pressed and much wider than the others, bearing a closely placed 

 double series of 30, or even more, slender, blunt spinelets, having 

 the appearance of an immense pectinate pedicellaria. Usually only 

 1 is slightly enlarged on the furrow. 



Combined mouth plates rather long and narrow, encroaching con- 

 spicuously upon actinostome and with a flaring marginal series of 



7 or 8 slightly flattened round-tipped spines, which increase at first 

 slightly, then rapidly, toward the inner heavy tooth, which is subterete. 

 or slightly compressed. The surface of the plate is occupied by 2 

 crowded rows of about 18 spines, those near the inner half of the 

 plate similar in form to the teeth though a trifle smaller. On the 

 outer half of the plate the spines adjacent to median suture increase 

 in length ^nd assume a lanceolate form, while the spines of the other 

 parallel series usually decrease markedly in length, so that at the 

 outer end of the plate there is but 1 conspicuous series of spines. 

 Sometimes these superficial spines are subspatulate. The lateral 

 carries a series of small, spaced, slender spinelets, much smaller than 

 those of the adjacent first adambulacral. 



Madreporic body small, very convex, with irregular striae, and 

 situated about midway between the center and margin of disk. 



Color in alcohol, rather dark brown. 



Anatomical notes. — Gonads in numerous closely crowded tufts 

 attached to the genital stolon, and extending about one-third the 

 length of the ray, close to the marginal plates. Each genital tube 

 is either simple or with a few branches. Intestinal coecum spacious, 

 saclike, in 3 unequal lobes, one of which being partly divided gives 

 the appearance of 4. The form is very nea-rly the butterfly shape 



