AMMOTKYPANE AITLOGASTEP. 17 



Head (Plate XCV, fig. 3 a), conical, pointed anteriorly and terminated by a stalked 

 mucro. It is rounded dorsally, slightly flattened ventrally, the rounded lateral muscular 

 ridges ceasing before the tip is reached. 



Body (Plate XCV, fig. 3), 1—3 in., elongated, fusiform, smooth to the naked eye, but 

 showing transverse striae under a lens. It is tapered about equally at each end, the anal 

 process, however, giving a somewhat more pointed condition posteriorly. The dorsum is 

 convex and marked by faint segment-lines, the ventral surface is grooved or flattened, the 

 lateral muscular ridges bearing the feet, which, in a large example, are fifty in number. 

 Posteriorly the ridges terminate at the base of the scoop-shaped tail in two somewhat 

 clavate cirri. 



The entire animal has a fine, bluish, pearly iridescence. It is dusky yellow on the 

 dorsum with brown touches, from the intestine : or pale anteriorly, then brownish ; with 

 the intestinal region greyish. The tail is pale or tipped with red. The under surface is 

 of a pale flesh-colour, and with a pearly iridescent lustre throughout. The dorsal cirri 

 have a red central streak. 



The foot (Plate XCV, fig. 3 d) consists of a long dorsal cirrus, somewhat constricted 

 at its base — which is at the upper border of the prominent muscular fillet at the ventral 

 region — then enlarges, and again tapers to the extremity. Its length at the anterior 

 third is fully the vertical diameter of the body, but it diminishes anteriorly and posteriorly, 

 and it is somewhat flattened. The transverse vessels give a barred appearance to the 

 organ as a transparent object. Immediately beneath is a combined setigerons process and 

 a short ventral cirrus. The bristle-tuft is very slender, consisting of long, slender, simple 

 hairs (Plate CIII, figs. 3 and 3 a), tapering to a delicate point, and with fine longitudinal 

 lines. A longer and a shorter series of bristles would seem to indicate that the tuft is 

 double, as Dr. Johnston mentioned. The slender iridescent hairs emerge close to and 

 somewhat beneath the anterior base of the branchial process (dorsal cirrus), and are 

 directed, as a rule outward and backward. The short ventral cirrus is disproportionately 

 small. 



The great ventral muscular bands pass backward— diminishing toward the tail — 

 until they cease (as external objects) at the base of the two rather thick cirri, which are 

 slightly fusiform and with blunt tips. These cirri arise close together, and mark the 

 commencement of the caudal process or scoop, the hollow of which is ventral and the 

 convexity dorsal, the posterior end forming a pointed and hollow cone. The inner border 

 of the ventral edge has a series of well-marked papillae or short cirri (Plate XCV, figs. 

 3 b and 3 c), for in well-preserved examples from St. Magnus Bay (1 00 fathoms), this process 

 has a long median cirrus above the ventral pair, the arch of the hood has regular trans- 

 verse striae, and the tip, which curves downward, terminates in a small median cirrus, 

 whilst the edges are fringed. This delicate apparatus is frequently imperfect. Fauvel 

 has also noted the occurrence of this unpaired cirrus. The apparatus evidently has 

 special functions in life, and differs from those in which the anal scoop has its concavity 

 directed dorsally. It is possible that the abbreviated condition of the body and its habits 

 in the sand necessitate a different mode of ejecting the effete matter. 



Habits. — The extraordinary activity and vigour of the living animals at once attract 

 attention. They exceed most annelids in the display of violent muscular action, as they 



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