LEPREA LAPIDARIA. 167 



two examples on a Pinna (Laughrin) ; west coast of Ireland, rare (Southern) ; in crevices 

 of shale, Plymouth (Spence Bate and B. Rowe, Allen and Todd). 



Extends to the Mediterranean and all its bays; channel shores of France (De 

 Quatrefages) ; shores of Cantabria (Rioja, De St. Joseph). 



The cephalic plate has a well-marked dorsal rim which curves laterally to become 

 continuous with the highly-arched supra-oral fold, often thin anteriorly. It bears 

 numerous slightly grooved tentacles, which also differ from those of many other forms in 

 firmly adhering after preparation. They are pale yellow in life, with the red blood-vessel 

 in the centre. The buccal process or " tongue " inferiorly often projects as a smoothly 

 rounded mass obscuring the rim of the segment behind it. Eyes not always visible. The 

 structure of the cephalic region of this inhabitant of fissures in rocks does not differ 

 materially from those which dwell in more or less free tubes, except that the lingual 

 process or boss is large and that the tentacles show only a slight groove at the base, and 

 it seems to disappear from the rounded distal region, which is tapered and ends in a 

 slight knob. 



The body (Plate CXIII, figs. 3 and 3 a) is comparatively short and firm, has the 

 typical shape — enlarged in front and tapered posteriorly — whilst the dorsal surface is 

 smoothly rounded to the level of the ridges for the hooks, and the ventral surface is marked 

 by a deep groove behind the twelve to thirteen scutes. Anteriorly the dorsum is minutely 

 striated transversely, and behind the branchiae it is finely tessellated after the manner of 

 Scalibregma. On the ventral surface are about twelve central shields which are of a 

 brighter red than the rest of the body, and behind them a white median stripe (marking 

 the nerve-cord) is continued to the tip of the tail, where it blends with the pale hue of the 

 region. The first segment with its rim behind the lower lip is whitish, and each scute 

 has a transverse whitish streak at its posterior border. The ridges for the hooks are 

 somewhat paler than the general surface, and five of the anterior ridges have a glandular 

 white patch between them and the bristle-tufts — indeed, each setigerous process has a 

 glandular patch in front and behind. The dorsum throughout is dull brownish, inclining 

 to purple, in its native site, and merging into orange brown near the tip of the tail, at 

 which the anus is surrounded with small but distinct papillae (six to eight, De St. Joseph). 



The perivisceral fluid contains reddish corpuscles, and corpuscles containing haematin 

 also occur in the vessels. The intestine harbours numerous gregarines (De St. Joseph). 

 The branchiae are three in number on each side, the first the largest and the third the 

 least. Each arises by a short stem which divides somewhat dichotomously, but the 

 terminal divisions are both dichotomously and pinnately divided, the whole having the 

 aspect of a finely branched bush. In life they have a pale whitish-pink hue. 



Two ridges run from the ventral scutes toward the first branchia, but they are 

 devoid of hooks and bristles. The first bristle-tuft is borne by the setigerous processes 

 opposite the second branchiae (fourth segment). The pale golden bristles (Plate CXXVI, 

 figs. 8, 8' and 8 a) form two groups, a shorter and a longer. The longer (Plate CXXVI, 

 fig. 8 a) have cylindrical shafts up to a slightly narrowed region behind the wings, which 

 are minutely serrated at the edge, followed by a visible enlargement as the wings arise. 

 After tapering considerably the slightly curved axis ends in a translucent knife-blade 

 tip, the base of which is thickened into a process or spur representing the termination 



