4 LYMAN ON A NEW STRUCTURAL 



These soft little creatures illustrate how small an influence certain kinds of the notorious 

 "environment" have in determining structure. Of the two species of this abnormal 

 Ophiohelus, one comes from 82 fathoms, near the Barbadoes, and the other from 1350 

 fathoms, near the Fiji Islands. When we consider the differences of locality, light, pres- 

 sure, and temperature (differences which are supposed to create varieties, or species 

 so called), between these two stations, we may well be a little sceptical as to the potency 

 of such environment. 



These genera stand quite apart from others of the family and call for diligent renewal of 

 the endless search after those constantly increasing missing links. 



OrniOTHOLiA ^ gen. nov. 



Disk and arms capable of being raised vertically : the former covered by a delicate 

 scaling set with minute spines. Mouth-angles clothed with several rows of wide, flat 

 moutb-papillae, (as in Ophiomyces), and with a single row of slender, sharp teeth. On 

 outer joints of arms near margin of each side arm-plate is a tuft of minute, translucent, 

 supplementary spines or pedicellariae, Avhich have the foi-m of a long-handled parasol. 

 They stand a little inside the true arm-spines, which are continuous to the end of the 

 arm. 



Opliiotholia supplicans sp. nov. Plate I, figs. 1-3. 



Special marks. Three arm-spines. Pedicellariae beginning about the ninth joint and 

 arranged in clusters of three or four. 



Description of an individual. Diameter of disk (when the arms are raised vertically), 

 2 m.m. Height of same, 3.5 m.m. Width of arm without spines 0.8 m.m. Length of 

 arm, about 13 m.m. The mouth-angles are high and narrow, so that the mouth-slits 

 between them are wide : with their curved sides and sharp tooth at the apex the angles 

 bear a resemblance to a bird's head with a pointed bill. Three acute spine-like teeth, out- 

 side which, and partly encircling the large three-sided jaw plate, as with a frill, is a trans- 

 verse, curved, erect, close row of eight or ten long, narrow, flat papillae. Again outside 

 these, and on the jaws and mouth-frames are three parallel transverse rows of erect foliate 

 papillae — the first row has six papillae, which are smaller than some of those beyond, 

 but, like them flattened and widest at the free end ; the second row is similar ; while the 

 third usually consists only of two jjajiillae much larger and wider than the others. These 

 rows quite obscure the base of the mouth-angle and mouth-shields. In general, the 

 arrangement is like that of Ophiomyces frutectosus. The above numbers are the maxi- 

 mum ; some angles have fewer papillae ; not more than four in a transverse row. In the 

 fresh specimen, under arm-plates are not visible, but, on partial drying, their outlines may 

 be seen. They are narrow, much longer than wide, wider without than within, with a 

 small angle within, lateral sides reenteringly curved, and outer side in a broken curve. 

 In like manner the side arm-plates are seen to meet broadly below, and to form a slight 

 spine-crest at their outer edge. Figure 2 shows the arm-joint from below, so covered by 

 the natural skin that the junction of the side arm-plates on the central ridge cannot be 

 seen. Disk sugar-loaf shaped and sparsely set with minute spines, each of which, in the 



' '0<?frt a snake; HoXia. a parasol. 



