PERIGONIMUS REPENS. 32a 



Colour. — Pcrisarc grcyish-ycUow, hydranth vermilion, medusa with its manubrium reddish, 

 and the basal bulbs of its marginal tentacles reddish-ljrown. 

 Development of Gonosome. — August. 



Habitat. — Attached to other hydroids, the tests of large ascidians, &c. 

 Batltymetrical distrihiition. — Coralline zone ? 

 Locality. — Coast of Xorway, Sars. 



I have never met with this species. The diagnosis given above is selected from the 

 characters published by Sars. The species is historically interesting as affording the first- 

 described example of a genns which we now know to be one of the richest in specific forms 

 among the gymno1)lastic hydroids. 



2. PERiGOxnius REPENS, SlretMll JFright. 



Endendrium pusillum, — IVrif/ht, in Proc. Roy. Phys. Soc. Ediu., vol. i, p. 231, \A. xi, 



figs. 8, 9. 

 Atr.-vctyles repexs, — IVriglit, iu Proc. Roy. Phys. Soc. Ediu., vol. i, p. 450, pi. xxii, 



figs. 4, 5. 

 Perigonimus repex.s, — Hincks, Brit. Hydr. Zooph., p. 90, pi. xvi, fig. 2. 



TROPHOSOME. — Htduocaultis simple, or slightly branched, attaining a height 

 of from one eighth to one quarter of an inch ; perisakc dilated at the summits of the 

 hydrocaulus. Htdrantiis partially retractile, with from four to twelve tentacles held 

 in an alternately elevated and depressed position. 



GONOSOME. — GoNOPHORES nearly sessile on the hydrocaulus ; umbrella thimble- 

 shaped ; marginal tentacles four, two opposite tentacular bulbs carrying very long 

 ones, and the others very short ones. 



Colour of hydranths white. 



Habitat. — " Attached to scrtularians, and to the back and legs of the spider-crab," Wright. 

 Localities. — Firth of Forth, Dr. Wright ; Coast of Northumberland, Mr. Alder ; Ilfracombe, 

 IMr. Hincks. 



I agree with Hincks in regarding the Atractylis repensoi Wright as the same hydroid which 

 he had previously described under the name of Endendrium pusillum. Indeed, it is impossible to 

 find any characters of specific value by which the one may be distinguished from the other. 

 Wright does not himself appear to recognise any difference between them, and while his change 

 of the generic name is founded on legitimate zoological grounds, his change of the specific name, 



42 



