126 E,ev. T. Hincks on Nonoegian 



against forty-two in the former. And the character of this 

 " deep-water " fauna is as remarkable as its richness. It in- 

 chides no less than thirteen of the sixteen undescribed species 

 obtained by Sars, and (probably) three new generic types. 



It is interesting to note the extended vertical range which 

 these investigations have established for several well-known 

 species. Thus Tuhularia indivisa^ which is common between 

 tide-marks on the English coast, has been taken up at a depth 

 of 200 fathoms ; Plumularia setacea, a common denizen of our 

 rock-pools, occurs only between 50 and 100 fathoms in the Nor- 

 wegian seas ; Mynothela, which is found near low-watermark, 

 ranges to 100 fathoms ; Podocoryne carnea is obtained on the 

 shore and from 200 fathoms, and Hydractinia echinata at low- 

 water mark and from 100 fathoms. It is also worthy of 

 remark that Sars has obtained from a depth of 400 fathoms a 

 Hydroid which he refers to Perigonimus^ an Athecate genus, 

 producing free reproductive zooids. In all previous cases the 

 species dredged from great depths have been such as are pro- 

 pagated by means of fixed sporosacs and not by planoblasts *. 



Passing to the descriptive portion of the paper, the first 

 point of special interest is the occurrence of a small group of 

 Pluraularian Hydroids belonging to the genus Aglaophenia. 

 This form is specially characteristic of warmer latitudes. On 

 our own coasts it is comparatively rare in the north and north- 

 eastern districts ; in Shetland it is represented by a single 

 species, A. myriophyllum. Still further north it has only oc- 

 curred in the deep-water region, to which dredging has recently 

 been extended. Near Stavanger, off the island of Hvitingso, 

 Sars has obtained three supposed new species of this fine 

 genus, in depths varying from 80 to 150 fathoms. An ex- 

 amination of this group of southern strangers, thus encountered 

 in the deep northern waters, discloses some points of interest. 

 They were obtained on a muddy bottom at very considerable 

 depths, and, we may therefore suppose, in one of the warm areas 

 to which our attention has been di'awn of late f- 



The first species described [Aglaophenia radicellata) is 



* Vide Allman's ' JMonogr. Tubularian Hydroids,' part ii. p. 165. It is 

 true that Sars did not actually observe the planoblast of his Perigo7iimus 

 abyssi; but he had the opportunity of examining the gonophores, and had 

 no doubt of the Medusan nature of their contents. 



t This is a mere conjectui'e, as we have no precise account of the nature 

 of the ground ; but the deep-water region oiF Hvitingso appears to possess 

 a rich and peculiar Hydroid fauna which suggests the inference that it 

 enjoys a comparatively high temperature. Allnian mentions a new Plu- 

 mularian genus, which was obtained during the cruise of the ' Porcupine,' 

 at a depth of 682 fathoms, in water where the temperature ranged from 

 30°-o Fahr. to 29°-8 Fahr. (' Tubularian Hydroids,' pt. ii. p. 165). 



