122 PORIFERA. III. 



characters, the acanthostyli are smaller and the ancorse in biscutella are described as having ten or 

 about ten teeth ("une dizaine"), and they are larger, 0-027 0-030 mm ; finally the present species does 

 not show the "cellules spheruleuses" mentioned by Topsent for biscutella. 



Locality: Station 6, 63 43' Lat N., 14 34' Long. W., depth 90 fathoms; station 32, 66 35' Lat. N., 

 56 38' Long. W., depth 318 fathoms; further it has been taken at 63 18' Lat N., 21 30' Long. W., depth 

 94 fathoms (The Fishery investigation steamer "Thor"); 61 40' Lat. N., 7 40' Long. W., depth 135 fathoms 

 (Ditlevsen); 62 23' Lat N., 2 35' Long. E., depth 217 fathoms (Ad. Jensen, the cruise of "M. Sars" 1902). 

 In all six specimens. The localities are situated in the Davis Strait, South and East of Iceland, West 

 of the Faroe Islands and between the latter and Norway. 



Leptolabis Tops. 



Incrusting forms ; external appearance, skeleton and megasclera as in Hymcdesmta; the dermal 

 spicules tylota; the characteristic microsclera are forcipes of one or two forms, to these are added chela 

 arcuata and sigmata. 



Topsent founded this genus in 1904 (Resultats des camp, scient. du Prince de Monaco, 

 Fasc. XXV. 181) and I think he was right, the presence of forcipes being here, as in the genus For- 

 cepia, of sufficient importance for the creating of a genus; moreover the dermal tylota seem to be 

 characteristic for the genus. 



The genus Leptolabis comprises at present the following species: 



1888. L. luciensis Tops. Arch, de Zool. exp. et gen. 2. VI, XXXVII, (Dendoryx). 

 1892. L. exilis Tops. ibid. 2, X, XXII, (Leptosia). 



1904. L. forcipula Tops. Resultats des camp, scient. du Prince de Monaco, Fasc. XXV, 182, PI. XV, fig. n. 

 L. forcipula var. brunnea Tops. ibid. 182, PL XV, fig. 12. 



L. arcuata Tops. ibid. 183, PI. XV, fig. 18. 



1905. L. irritans Thiele, Zool. Jahrbiicher, 1905, 455, Taf. 31, Fig. 7136 (Hymedesmia}. 

 L. assimilis mihi. 



I have remarked below, that I consider L. forcipula var. brunnea as a definite and separate 

 species; the same may I think be said with certainty about L. luciensis and exilis; on reading the description 

 of luciensis of 1904 I got the impression that besides exilis perhaps still a third species may be 

 hidden here. 



i. L. assimilis n. sp. 



PI. XI, Fig. 8. 



Incrusting; surface smooth. The main skeleton weak. Spicula: megasclera; the skeletal spicules 

 acanthostyli divided into two groups, large and small; the large without head, somewhat densely spined 

 in almost the whole length, 0-42 o-jj""*/ the small with a slight head, spined in about the lower half, 

 0-089 0-21"""; the dermal spicules tylota with small swellings, 0-380-50"""; microsclera four forms ; 

 chela arcuata 0-014 0-038'""', sigmata 0-077 o-i6 mm , spinulous forcipes of two forms, large, with legs 

 of equal length, 0-024 0-034""", small, with unequal legs, 0-014 o-oi8 mm . 



