154 Eev. T. Ilincks on the 



sinuated in front," or, as llie character is given in the diag- 

 nosis, " slightly channelled in front." 



This character is not very strongly marked, and in the 

 more highly calcified condition of the cell is often difficult to 

 detect. On young zco?cia in the marginal region of the 

 colony a shallow rounded sinus may be detected, though even 

 amongst these cells not unfrequently occur in which the 

 margin has all the appearance of being entire. In the case 

 of ohler zooecia, which are overlaid by a thick calcareous crust 

 and the orifice is sunk in a comparatively deep shaft, the sinus 

 will often be sought in vain. 



It is right to add that Mr. S. O. Ridley, who obtained the 

 species from Franz-Joseph Land, found the oral sinus " well 

 marked in most, even old cells " *. 



Lepralia pertusa, Esper. (PI. YIII. fig. 7.) 



There seems to have been a good deal of uncertainty about 

 this species ; I have therefore given a figure taken from a fine 

 St. -Lawrence specimen in which the characters are well 

 displayed. Smitt, in one of his later works f, identifies it 

 with his Escharella porifera (a near ally, if not a mere variety, 

 of Smittia Landshorovii)^ from which it is separated by 

 important differences. Of Busk's figures one or two are 

 referable to another species. Waters, in his ' Bryozoa of the 

 Bay of Naples,' has recorded two varieties of Lepralia per- 

 tusa, both of which probably are quite distinct from Esper's 

 species. 



Schizoporella cincta, Hincks, var. (PI. VIII. fig. 2.) 

 Lrpnrlia cincta, ' Annals/ ser. i), vul. xv. p. l'-")4, pi. viii. fig. 6. 



A variety of this New-Zealand species occurs amongst the 

 St. -Lawrence dredgings which is distinguished by a peculiar 

 condition of the cell-wall in the immediate neighbourhood of 

 the avicularium. In the typical form a prominent umbo rises 

 iniinediately below the orifice, bearing on its summit an elon- 

 gate pointed avicularium, placed transversely. In the variety 

 the umbo has disappeared or is reduced to a very slight and 

 inconspicuous elevation forming part of a distinct area of the 

 cell-wall, extending to a greater or less distance below the 

 orifice, sometimes almost orbicular, sometimes elongate and 

 stretching down about half the length of the cell. This area 



* ' Annals' for June 1881, p. 449. 



t (Efvcrs. Konffl. Vet.-Akad. Forlmndl. 1^78, — No. 7. I?ryozoa from 

 the Arctic Sia (lVniu.«u!a of Kola). 



