364 OPHRYOTROCHA PUERILIS. 



division compound bristles, the terminal process having a hook distally and a process 

 beneath it (Langerhans). 



Langerhans thinks that this form agrees with Delle Chiaje's rubra and vittata in 

 the upper bristles, but possesses only two eyes. 



The foot (Plate LXXXVII, fig. 9 a) differs from that of 8. rubrovittatus in the 

 inconspicuous condition of the two upper processes, but it more nearly approaches that of 

 8. Kefersteini. 



The dorsal bristles (Plate LXXXVI, fig. 10) are translucent, long, slender and finely 

 tapered, with serrations on the edge below the long smooth tip, whilst the bifid forms 

 (Ibid., fig. 10 a) have a longer and a shorter limb, about half a dozen serrations occurring 

 on the edge below the latter. The ventral series of falcate bristles (Ibid., fig. 10 b and b') 

 has the terminal piece long and slender as well as bifid. 



The exact position of the Plymouth example is uncertain. It may be immature. 

 The figures of Langerhans certainly differ from the structures observed in this form, 

 but they may not be accurate. 



Genus LXII. — Ophryoteocha, Glaparede and Mecznikotv, 1869. 



Small forms with horse-shoe-shapecl head ; eyes four ; two short dorsal tentacles in 

 front of the eyes, and two similar tentacles ventrally. Body comparatively short, first 

 two segments devoid of feet ; two clavate cirri posteriorly. Proboscis armed with a 

 complex upper dental apparatus, and an /-shaped mandible. Foot resembling that of 

 Staurocephalus, with simple upper bristles and compound lower bristles. Oviparous. 



1. Ophryotrocha puerilis, Glaparede and Mecm., 1869. Plate LV, fig. 9 — head and 

 anterior region; Plate LVI, figs. 4 and 5; Plate LXI, figs. 10 and 10 a — young 

 and teeth; Plate LXXIII, fig. 7— foot ; Plate LXXXI1, figs. 1 and 1 a— bristles. 



Specific Characters. — Head horse-shoe shaped, with palpocils anteriorly. Eyes 

 variable, generally four, two situated externally in a dimple behind the dorsal tentacle, 

 and two smaller on the summit of the head just in front of the nuchal fold. Occasionally 

 a pigment-spot or two in front of the latter. In front of each anterior eye a small 

 tentacle of two segments, the basal shorter than the distal. A pair of tentacles of similar 

 structure on the ventral surface. Body nearly half an inch long, of more than thirty 

 segments, slightly tapered at each end, pale and translucent. First two segments 

 devoid of feet. Two clavate cirri posteriorly. Proboscis with dark brown or blackish, 

 strongly curved maxilte, and with an acute posterior process. Six denticles beneath and 

 in front, each hoof-shaped, with the free edge denticulated, and diminishing in size 

 from before backward. Mandible elongated and curved like the letter /, cutting 

 edge bifid, each cusp being arcuate. Foot resembles that of 8taurocephalus, with four 

 conical terminal processes. At the upper end is the conical dorsal lobe. Beneath is a 

 conical process for the spine, one margin of the foot trending obliquely into the setigerous 



