~. PORIFERA. II. 



expressly says of placoides that the spicules projecting through the dermal membrane are smaller than 

 the others, while his other description agrees very well with the specimens before me. I have then 

 determined the other species as lingua, but from the description of Bowerbank it is not to be seen 

 with certainty, whether he has possibly had placoides or perhaps both species before him. Topsent, 

 1. c. 1892, enumerates both lingua and placoidcs, but gives no description, so that it cannot be seen, 

 which characters he takes to be the distinguishing ones. The peculiar handle-like formation of the 

 upper end of the styli cannot be used, as this formation, as is seen from the preceding descriptions, 

 is found in both species, and may occur very varying with regard to its frequency and degree of 

 marking. Therefore I also follow Topsent in regarding Bowerbank's lingua and const ricta as one 

 species. When Topsent in the place quoted mentions that he has seen specimens of lingua with pore 

 furrows, and others without such and with a uniform, slightly shaggy surface, I must suppose that in 

 the latter the pore furrows have been closed, the slight keels then found being often only very little 

 conspicuous. 



I have omitted to quote Esperia constricta Vosmaer (Niederl. Arch, fur Zool. Suppl. Band I, 

 1881—82, 45), and Esperia lingua Vosmaer (Bejdr. tot de Dierk. i2 te Afl. 3 die Gedeelte, 1885, 30), as it 

 is impossible to decide, which of the two species mentioned here the author has had before him. The 

 figures in the former place, PI. Ill, fig. 99, and in the latter place, PI. V, fig. 73, might both look like 

 dermal spicules of M. placoides, but nothing can be decided with certainty. Neither have I quoted 

 Esperia constricta Marenzeller (Die oesterreich. Polarst. Jan Mayen, III, 10), the author's good and 

 rather copious account of the variation of the spicules would seem to indicate that he has had both 

 species before him. Thus with regard to the geographical distribution we can, from these facts, only 

 infer that one or the other, or both species occur in the Barent Sea between 72 and 75° Lat. N., and 

 between 15 and 36 Long. E., on depths between 128 and 175 fathoms, as well as at Jan Mayen on 

 depths from ca. 48—200 fathoms. The E. Vosmaer i established by Levinsen 1. c. I have, by an 

 examination of the type specimen, found to be identical with M. lingua; Levinsen does not 

 mention rhaphides, which, however, are present. The E. murrayi established by Ridley and Dendy 

 Challeng. Report, XX, 67, PI. XIII, figs, n, 13, 14, 16, 17, 18; PI. XIV, figs. 1, 1 a) is by Topsent 1. c. 

 referred to E. placoides, and by Lambe 1. c. to E. lingua. If the chela figured by Ridley and Dendy 

 fig. 17 is correct with regard to the tooth of its smaller end, a specific identity with placoides or 

 lingua is out of the question, neither does the description of the dermal skeleton or the length o-053 mm 

 given for sigmata agree with any of the two species. The E. lingua var. arctica established by Fri- 

 stedt (Vega Exp. vetensk. Iakttag. IV, 449, PI. 25, figs. 20—24, PI. 29, fig. 18) cannot be E. lingua, 

 only on account of the measures given for the spicules, but must be another, independent species. 



3. M. ovulum O. Schmidt. 



PI. I, Figs. 6—8, PI. X, Fig. 1 a— e. 



1870. Chalinula ovulum O.Schmidt, Grundzuge einer Spongienfauna des atlant. Gebiet, 38, Taf.V, Fig. 1 '). 



1873. °- Schmidt, Jahresber. d. Coram, zur wissensch. Unters. deutsch. Meere in Kiel 



fiir 1871, 99. 



') In the explanation of the plate the name, presumably by a misprint, is Chalinula ovum. 



