THE CRAG POLYZOA. 



which represents the opening of a concealed ovicell, is termed the ovarian orifice or 

 pore. 



3. The secondary openings, often of considerable size, observable at the apex of many 

 of the cells, having been shown by observation of recent forms to belong to avicularia, 

 are termed accordingly ammlarian openings. 



1. SALICOKNARIA CRASSA, S. Wood (sp.) PI. XXI, figs. 4, 6. 



Internodiis crassis, clavatis, subcompressis ; cellulse orificio infra, denticulo valido 

 acuto, interne utrinque munito. Ovicellula3 orificio dente conico unico infra armato ; 

 cellulse facie anteriori linea elevata utrinque signata. 



Internodes thick, clavate, sometimes compressed ; a large tooth on each side of the 

 orifice within the lower border ; a single conical tooth on the lower border of the 

 ovarian pore ; a narrow raised line on the front of the cell on either side of the mouth, 

 meeting below. 



CELLAKIA CBASSA, S. Wood, Ann. Nat. Hist., xiii, p. 17; Morris's Catal., p. 120. 



Habitat. Cov. Crag, S. W. 



This species appears to exhibit a very great tendency to ossification of the junctions 

 between the internodes ; so much so, in fact, that most of the specimens present a 

 bifurcate aspect at one end. The avicularian arese are quadrangular, with a circular 

 aperture, whence it is probable that the mandible was rounded or obtuse, as in Sal. 

 farciminoides. The surface of the cells and of the ridges, so far as can be judged of in a 

 fossil, are smooth or very finely granular ; and the front of the cell within the area is very 

 peculiarly marked by the presence of two slender, straight, raised lines or ridges, which, 

 commencing at the sides of the area, about on a level with the upper border of the mouth, 

 descend on either side and meet towards the lower part of the cell. These lines are shown, 

 but not very distinctly, at d, fig. 4, and c, fig. 6. Rounded raised lines, much in the 

 same situation, are occasionally to be seen in Sal. farciminoides, but these do not appear 

 to meet below, and are far less constant in that species than the lines in question are in 

 S. crassa. The single conical tooth in front of the ovarian opening is also characteristic 

 of S. crassa. In S. farciminoides this opening is unarmed, and at first narrow and 

 elongated longitudinally, whilst in S. crassa, at its earliest appearance, it is round and 

 afterwards elongated transversely with the tooth in question on its lower margin. The 

 proper form of the tooth is seen in the lowermost cell in b, fig. 4 ; in d, fig. 6, it is repre- 

 sented bifid, but this is an accidental appearance, and probably due to injury. 



