ONUPHIS BRBVIBRAOHIATA. 407 



The tubes (Plate LXIII, figs. 7 c and 7 d) are formed of the tough translucent 

 secretion of the glands, strengthened by pieces of shell, or sometimes attached to an entire 

 valve of Pecten. Special attention has been paid to the nature of the protective internal 

 valves of this species by Mr. Arnold Watson 1 (his Onuphis conchilega), and he figures two 

 arrow-like va]ves at one end, but whether anterior or posterior is uncertain. The species 

 appears to carry about its tube caterpillar-fashion (Watson). In the Zetlandic examples 

 such bivalves as Nucida, Leda, and Lucina are frequent. 



This species has certain resemblances to the Diojpatra socialis of Ehlers (1875) from 

 the c Porcupine ' Expedition of 1869, but, amongst other features, it diverges in the 

 position of the tentacular cirri ; the simple nature of the branchiae throughout, whereas 

 in D. socialis they are simple, bifid, or trifid ; by the fact that they arise on the tenth 

 segment; and in the nature of the tube, which in D. socialis is secretion and mud. 



The relationship of Nothria conchyphila of Verrill (1885) remains uncertain, but it 

 " constructs flat free tubes, about 2 ins. long, out of broken bivalves, and often occurs in 

 vast numbers in the warm zone," viz., off the northern coast of the United States. The 

 critical points are unfortunately not shown in the figures ; indeed, the Hyalinoecia artifex 

 of this author likewise closely approaches the British form. 



2. Onuphis blievibraohiata, Elders, 1875. Plate LXIII, figs. 8 and 8 a — teeth; figs. 10 

 and 10 a— head ; Plate LXXV, figs. 6 and 6 a— feet ; Plate LXXXIV, figs. 4-4 c— 

 bristles. 



Specific Characters. — Head with two rounded and flattened frontal tentacles. 

 Tentacles short, arising from a ringed cirrophore. Tentacular cirri slightly fusiform 

 from a constriction at the base. Palpi form two flattened bosses ventrally. Body 

 resembling that in Hyalinoecia. Dental apparatus has strongly curved maxillae, which are 

 sharp at the point and rather abruptly swollen a little behind the middle. The posterior 

 appendages are half-spoon-shaped, with a constriction at the base. Great dental plates 

 have about ten teeth, and the azygos plate has the same number. Right anterior curved 

 plate has five teeth ; left broken, but appears to have more. Mandibles with an oblique 

 smooth edge anteriorly, and an external projection. Branchiae commence on the twelfth 

 foot, are simple as far as the sixteenth foot, the seventeenth having a branched branchial 

 process, the twentieth a simple base attached to the cirrus, and the rest being dichotomously 

 divided. The thirtieth branchia has three divisions, and then the tip is dichotomously 

 divided. First three feet much larger than the succeeding, more or less ventral in 

 position, flattened and directed outward. Ventral cirrus of the first shifted, so that it 

 adjoins the mouth. The tenth foot has a subulate dorsal cirrus with a ventral hiatus 

 followed by a swelling from which it tapers to the point. It is supported by slender 

 spines, the blunt points piercing the tip, and a short flap projects posteriorly. Dorsal 

 bristles long, translucent, slightly curved, and finely tapered— with narrow serrated wings. 

 Ventral bristles translucent, shafts enlarged and bevelled distally for articulation with the 

 long tapering terminal piece. The latter kind of bristles disappear at the twentieth foot, 

 1 ' Trans. Liverp. Biol. Soc./ vol. xvii, p. 311, pi., fig. 8. 



