130 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



first arm segments. The rather numerous arm spines are elongated, 

 fine, often echinulated, and the two lateral rows never come close 

 together in the median dorsal line at the base of the arms. There is 

 a single tentacle scale. 



Notes. — The type of the genus Ophiomelina is O. placida. which at 

 the time I described it I placed in the genus phiomitrella , and which 

 the Albatross has rediscovered in the Philippines ; the genus also in- 

 cludes OpMomitrella moniliformis Kcehler and 0. micro phylax H. L. 

 Clark. 



In 1915 H. L. Clark placed O. placida in the genus Ophiacantha, 

 but this disposition can not be maintained, for in all its characters, 

 and notably in the upper and under arm plates, in the arm spines, 

 and in the covering of the disk, this species differs markedly from 

 all the known species of Ophiacantha. 



Type of the genus. — Ophiomelina placida (Kcehler). 



OPHIOMELINA PLACIDA (Kcehler). 



Plate 30, figs. 8, 9 ; plate 94, fig. 3. 



OpMomitrella placida, Kcehler ('04), p. 137, pi. 31, figs. 3, 4. 

 Ophiacantha placida H. L. Clark ('15), p. 207. 

 OpMophthalmus placidus Matsumoto ('17), p. 106. 



Localities. — Albatross station 5618; Molucca Passage; Mareh Is- 

 land bearing S. 69° E., 14.45 kilometers (7.8 miles) , distant (lat. 0° 

 37' 00" N., long. 127° 15' 00" E.) ; 763 meters (417 fathoms) ; No- 

 vember 27, 1909 ; gy. M. 



One specimen (Cat. No. E. 55, U.S.N.M.). 

 . Albati'oss station 5629; Patiente Strait and southward; Doworra 

 Island (S.) bearing S. 62° W. 11.1 kilometers (6 miles) distant 

 (lat. 0° 50' 00" S-., long. 128° 12' 00" E.) ; 375 meters (205 fathoms) ; 

 December 2, 1909 ; co. S. 



Two specimens (Cat. No. E. 53, U.S.N.M.). 



Albatross station 5661; Flores Sea; Cape Lassa bearing N. 21° E. 

 23.16 kilometers (12.5 miles) distant (lat. 5° 49' 40" S., long. 120° 

 24' 30" E.) ; 329 meters (180 fathoms) ; December 20, 1909; hrd. 



One specimen (Cat. No. E. 54, U.S.N.M.). 



Notes. — The specimens from stations 5618 and 5629 bear granules 

 only on the dorsal surface of the disk (pi. 94, fig. 3) ; on that from 

 station 5661 the central region shows very fine and very short club 

 spines terminated by a few asperities, and these club spines gradually 

 transform into granules toward the periphery of the disk. 



In the specimen from station 5618 the disk is strongly excavated 

 in the interradial spaces, and it is still more so in the two specimens 

 from station 5629, but without enabling it to be said that it is really 

 notched. In the specimen from station 5661, shown in figure 8 on 

 plate 30, it is seen that in three interradii the notches are continued 



