412 ONUPHIS CONCHYLEGA. 



armature (Plate LXIV, fig. 1) resemble in colour and general aspect that of Onuplds 

 britannica. The T-shaped dark bands are conspicuous at the posterior appendages, and 

 a dark patch occurs at the posterior end of each great dental plate. The aspect and 

 curvature of the maxillaa are the same. A little in front of the posterior appendages an 

 incurvation of the inner edge of each occurs, connected by the dark mass with the 

 base of the great dental plate. The right great dental plate has nine teeth and a 

 posterior ridge; the left has eight and a ridge. The azygos plate (left) has nine or 

 ten teeth. The curved anterior plate on the left has nine or ten teeth; that on the 

 right has about twelve. Each of these plates has a dark brown base. A single isolated 

 denticle occurs beyond (anterior to) each curved process. The mandibles (Plate LXIV, 

 fig. 1 a) have a single denticle on the oblique edge in front and long tapering shafts. 

 The outer edge is pointed. The segment following the peristomial is about the same 

 breadth and carries the first pair of feet, which are shorter than in 0. britannica, have a 

 nearly circular flap at the tip, though this varies in different specimens, and a little 

 within it arises the subulate dorsal cirrus. Posteriorly is a blunt and nearly 

 cylindrical papilla, and ventrally, on each side of the under lip, is a short, thick 

 ventral cirrus with a slight constriction at the middle, as if a cirrophoral differentiation 

 existed. The foot forms a short cone supported by three tapering spines, and with 

 a series of long and strong falcate bristles (Plate LXXXIV, fig. 5), the tip of which is 

 boldly hooked, with a small secondary process or ridge a short distance beneath. From 

 the edge of the hook below the ridge, wings extend forward to the tip. In the de- 

 veloping hook the part first formed is the tip, and it is then seen that the secondary 

 process attains no larger size than what is figured and described (Plate LXXXIV, fig. 5 a). 

 In many examples, however, the tip forms a rounded blunt hook without a trace, or 

 only with a very slight trace of the secondary process, and devoid of wings, a 

 condition probably due to attrition. The tip as a rule remains boldly hooked. The 

 structure of the foregoing bristle or hook is fundamentally different from that of Onuphis 

 britannica. 



The second foot forms a still shorter conical process, also usually directed forward, 

 and having a rounded flap projecting from the tip. The dorsal cirrus is subulate, con- 

 siderably longer than in the first foot, and arises from the middle of the dorsum. The 

 papilla from the posterior edge of the tip of the foot is long and subulate. The ventral 

 cirrus has nearly the same form and size as in the first foot, the constriction indicating 

 the ceratophore being clearly marked. Dorsally are short simple bristles which have only 

 a trace of wings, and brush-shaped forms, the long and stout hooks beneath being the 

 conspicuous appendages. Each hook has the structure already described, the tips of 

 those projecting being blunt from wear. The third foot has still further diminished, 

 though the dorsal cirrus is longer. The terminal button-like flap is smaller, the posterior 

 papilla is long, but the ventral cirrus is a short ovate lobe attached to the base of the foot 

 ventrally. The bristles and hooks are the same. 



The tenth foot has a long subulate dorsal cirrus arising from the base (Plate LXXV, 

 fig. 7), a short conical setigerous region, with a minute button-like papilla at the tip, and 

 a long posterior papilla. The ventral cirrus now forms a rounded boss which is becoming 

 less and less prominent. The setigerous region has stout simple bristles with the tip bent 



