160 AMPHIPORUS SPECTABILIS. 



towards these furrows so as to produce a similar appearance to that in Amphiporus spectahilis, 

 Quatref., but less marked in the lateral regions. The ganglia lie quite behind the trans- 

 verse furrow, as indicated by the shading in the figure. 



This species is often found in crevices of the coils of Serpulce attached to shells and stones 

 from deep water, and it is one of the most interesting of the group. It glides over the bottom of 

 the vessel with considerable speed, almost without a wrinkle of its body ; and when irritated a 

 healthy example turns on its edge, and, by sw T ift lateral strokes of the oar-like posterior extremity, 

 swims rapidly through the water like a Nephelis or a horseleech, so that not infrequently the 

 uninitiated mistake it for a species of the latter. In contraction the head is drawn within the 

 anterior portion of the body, the neck forming a kind of collar through which the organ slips 

 inwards. 



It rapidly secretes a tough sheath of transparent and iridescent mucus, under which it remains 

 for days. The skin presents an alkaline reaction to test-paper. 



The ova are developed in the beginning of May and are nearly ripe towards the end of June, 

 but though many ova have been discharged in the vessels, I have hitherto been unable to watch 

 their development. 



While, for a time, of opinion that the Tlanaria rosea of 0. F. Miiller {' Zool. Danica') might 

 refer either to this or the previous form, I now think that in all probability this species has the 

 preference in the description and figure. He says, "Body elongate, sub-equal, convex above, of a 

 rosy colour, marked with black points and lines (not distinct in some) ; flat beneath, of a pale 

 red interrupted with transverse striae, posterior end blunt, anterior produced into an angular 

 head; the latter is marked on each side by a semicircle of black points." The figure (which 

 has its anterior end downwards) bears a considerable resemblance to this form, especially in the 

 head and position of the eyes. His remark, however, that it is common everywhere leaves a certain 

 degree of doubt, and I have therefore chosen Dr. Johnston's title. The latter author was the 

 first to give a proper account of the species, from specimens procured amongst corallines and old 

 shells in deep water off the coast of Berwickshire. He noted the appearance of the ova in the 

 female, describing them as a series of bright scarlet spots along the sides. Sir J. Dalyell men- 

 tions a stripe, generally yellowish, which runs down the back, and a broader stripe along the 

 ventral surface, but these probably refer to the colour of the digestive canal. Pair figures of the 

 structure of the proboscis and the external appearance of this species are present in Gaimard's 

 ' Voyages en Scandinavie, en Laponie/ as mentioned in the zoography. 



I have not thought it necessary to include all the synonyms given by CErsted and Diesing, 

 since it is doubtful to what species they refer. 



3. Amphiporus spectabilis, De Quatrefages. Plate III, figs. 2, 7, and 8. 



Specific character. — Head spathulate, peculiarly narrowed posteriorly. Eyes in two long rows 

 on each side. Cephalic furrows conspicuously branched. Longitudinally striped with brown on 

 the dorsum. 



