222 



BULLETIN OF THE 



f 10 thin equal arm- 

 spines ; underarm- 

 plates encroached 

 nn by side arm- 

 plates. 



Disk, under 

 its granula- 

 tion, covered 

 with niiiiut 

 and smooth 

 scales 



P. i-estita Fbs. 



Pores only be- 

 tween first and sec- 

 ond under arm' 

 h I Plates. 



P. maculata Vll. 



Pores between the 

 under arm-plates 

 continued for some 

 distance along the 

 arm . 



7- S conical arm-spines, the lowest It, • ,,, 



one a little the longest ) P "Ptemspinosa Ltk. 



8- 9 flat, pointed arm-spines: the ) 

 lowest one very long and flat, often [ P. rigida Lym.* 

 equal to two joints in length. ) 



Pectinura (OpMarachna M. T.) infernalis. The original at Leyden is 

 lost: but among the unsorted specimens of the Museum Gotleffrov at Ham- 

 burg I found a specimen from near .Sumatra. It was unmistakable, and is 

 figured, Plate VII., Fig 1. I found another specimen from the Philippines, 

 by Semper. 



Pectinura septemspinosa. The original of Midler and Troschel from 

 the Moluccas is yet at Leyden, and remains unitpie. Diameter of disk 25 

 mm. Arms stiff, thick, cylindrical. Disk closely and evenly granulated, 

 with a smooth surface not indicating the scales below ; six grains in a mm. 

 long. Radial shields small, oval, brown and very distinct. Usually seven 

 arm-spines, but, on the inner joints, eight; they are conical, not so long as a 

 side arm-plate ; the lowest one a little the longest, and having its base cov- 

 ered by one of the tentacle-scales. The under ami-plates within the disk 

 have pores between them. Supplementary mouth-shield small. Color, yel- 

 low-brown. On Plate VI., Figs. 10-13, are shown the peculiar broken 

 upper arm-plates of this species ; an angle of the mouth ; and a row of arm- 

 spines. 



Pectinura marmorata sp. nov. 



riate V., Figs. 1-7. 



Special Marks. — Pores only between the first and second under arm- 

 plates. Arms somewhat widened at their insertion in the disk. Eleven 

 arm-spines. 



Description of a Specimen. — Diameter of disk 20 mm. Length of arm 

 about 105 mm. Width of arm at disk 4.7 nun. Height of the same 4.7 mm. 

 Fourteen small, close-set, tooth-like mouth-papillffl to each mouth-angle, of 



* Mr. F. W. Hutton (Catalogue of the Echinodermata of New Zealand, 1872) has described an 

 Ophium ( Ophiarachna ') cylindrica. It is earnestly to be desired that general zoologists, who have 

 not large collections for comparison, should abstain from describing species. For such persons, thus 

 situated, to give useful diagnoses is simply impossible. They only add to the confusion already 

 existing. Zoology, so far as concerns genera and species, has now passed into the hands of special- 

 ists ; and they alone can treat such subjects. 



