158 AMPHIPORUS PULCHER. 



This is a very common animal, generally lurking under stones between tide-marks, whether 

 these rest on sand, gravel, or sandy mud, and sometimes the latter is odoriferous ; thus at Herm 

 it frequently lives amidst crushed and blackened fragments of Zostera marina and sea-weeds under 

 stones. In such situations it generally resembles in contraction a cream-coloured larva, but 

 when placed in sea-water it readily extends itself and crawls with a slow gliding motion, and 

 likewise progresses on the surface of the water with the ventral region uppermost. It lives well 

 in confinement, and numerous broods can be reared from captive specimens. The white 

 ova are deposited in a free condition from January to April, and the young are from the 

 first furnished with two eyes. I have not been able to see this species feed in confinement, 

 but the rapid fattening in the free condition after spawning shows that it takes nourishment 

 greedily. 



The skin presents an acid reaction to test-paper, and the mucus secreted thereby is of a 

 most tenacious description, the animal, indeed, rapidly forming an investment by this means when 

 placed in a vessel containing a little sand. 



Considerable confusion has prevailed with regard to this very abundant and widely distri- 

 buted species. Johnston, CErsted, and others have considered the Planaria rosea of 0. F. Miiller 

 referable to this form, but, as will be noticed elsewhere, a careful consideration of all the facts has 

 led me to a different conclusion. When descriptions and figures are so vague and uncharacteristic, 

 it is impossible to clear away all doubts, but such uncertainty cannot be laid to our charge. The 

 earliest reliable account of the species is, perhaps, that given by Pallas in his ' Miscellanea Zoo- 

 logica/ but the specific name {pxyurus) there given is objectionable, and I have consequently 

 adopted another. Dr. Johnston, amongst modern authors, first clearly described this common 

 worm, and since his period less difficulty has been encountered in regard to its discrimination. 

 This author changed the name originally applied by him to the species from various causes, none 

 of which, however, interfere with our following the usual laws of zoological nomenclature. For 

 some time I was inclined to include the Amphiporus albicans of Ehrenberg under the synonyms, 

 as it has many characters in common, but it approaches A. pulclier in others, and the arrange- 

 ment of the eye-specks in his figure is so different that I have struck it off. For the same reason 

 the Planaria elongata of Montagu (MS. p. 231) was not included. The Polia manclilla of De 

 Quatrefages, from St. Vaast, probably belongs to this form, and there is nothing in the slight differ- 

 ences noted in Polia mutabilis, P. violacea and P. berea to distinguish them from the same 

 worm. The P. glauca of this author is also, in all likelihood, a dark variety of the species. 



2. Amphiporus pulcher (0. F. Miiller), Johnston. Plate I, fig. 3, and PL XIV, fig. 11. 



Specific character. — Eyes well-defined and numerous, irregularly grouped on each side. A 

 central reserve-stylet in the proboscis. Cephalic furrows slightly branched. 



Synonyms. 



1774. Fasciola rosea, O. F. Miiller. Verm, terrest. et fluv. hist., i, 2, p. 58. 

 1776. Planaria rosea, Ibid. Zool. Danic. Prodr., p. 221, No. 2679. 

 1788. „ „ Ibid. Zool. Danic, ii, p. 31, tab. 64, f. 1 and 2. 



