636 ECHINODEEMATA 



OPHIODERMA Miiller and Troschel. Disc granular, with 4 bursal 

 slits in each interradius; brachial spines short and smooth: 18 species; 

 littoral, tropical, and mainly West Indian. 



0. brevispina (Say) (0. olivacea Ayres) (Fig. 984). Disc pentag- 

 onal, 10 to 15 mm. in diameter ; length of arm 40 to 60 mm. ; color green 



or brownish: Cape Cod southwards, from 

 the shore to 120 fathoms; common towards 

 the south. 



FAMILY 2. OPHIOLEPIDIDAE. 



Oral papillae present; disc covered by 

 scales or plates; arm plates regular, the lat- 

 eral plates bearing small, closely lying 

 spines: 25 genera. 



OPHIUEA Lamarck. Disc with scales 



Fig. 934-7- Ophioderma or plates; indentation of disc at the base of 

 brevispina (Clark). 



usually fringed with m i nute spines 

 called the arm comb ; 2 bursal slits in each interradius : over 100 species ; 

 cosmopolitan. 



0. sarsi Liitken. Disc with several large scales surrounded by small 

 ones; arm comb made up of slender spinelets; 2 scales to each tentacle 

 on middle of ray ; diameter of disc 15 to 25 mm. ; length of arm 50 to 100 

 mm.; color olive or brown: Casco Bay and northwards, in 10 fathoms 

 and more; often very abundant; Europe; North Pacific. 



0. robusta (Ayres). Diameter of disc 10 mm.; length of arm about 

 30 mm.; disc covered with small scales; 1 scale to each tentacle; color 

 reddish: Cape Cod and northwards, from the 



shore to 150 fathoms; Europe. 



FAMILY 3. AMPHIURIDAE. 



Oral papillae present, fringing the mouth; 

 plates regular and distinct, the lateral arm 

 plates bearing small, solid spines, which stand 

 out from the surface of the arm: about 25 Flg . 935 OpMopholis 

 genera. aculeata (Clark). 



1, OPHIOPHOLIS Miiller and Troschel. Arm spines rather stout and 

 conspicuous; each upper arm plate surrounded by a series of small 

 plates; aboral surface of disc covered with scales bearing granules or 

 small spines: 5 species. 



0. aculeata (L.). Daisy brittle-star (Fig. 983 and 985). Upper 

 arm plates transversely oval; disc spines usually wanting in Atlantic 

 coast specimens ; color extremely variable ; diameter of disc 2 cm. ; length 



