200 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



axonosts. As therefore the first axonost of the anal fin 

 supports two baseosts completely and another partially, it 

 follows that it has been formed of at least 3 axonosts fused 

 together ; but, as before remarked, we have no direct 

 evidence of this.t The first baseost is situated in a de- 

 pression and the succeeding two on an elevation on the 

 postero-ventral surface of the first axonost, whilst the 

 second axonost is closely opposed for its whole length to 

 the same surface. The axonosts 3 to 7 fit by their tips 

 into a posterior longitudinal furrow borne on the first. 

 It is obvious that, as the first axonost is situated between 

 vertebrae 13 and 14 and axonost 7 lies in front of the 

 haemal spine of the latter vertebra, axonosts 1 to 7 and fin 

 rays 1 to 8 are situated in a space bounded morphologi- 

 cally by two adjacent vertebra). As previously men- 

 tioned, in only one other part of the body are as many as 

 4 axonosts found in a corresponding position. 



The posterior extremity of the anal fin presents no 

 features of special interest except that the last fin ray 

 articulates with the last axonost without the intervention 

 of a baseost. 



The mechanism of the fin ray has now to be described 

 (see fig. 16). Each ray consists of two longitudinal 

 distally segmented pieces (F.R. a, b) held together by a 

 transverse ligament (F.R. c). Proximally these two 

 pieces diverge and embrace the baseost (13s.), and also to 

 a limited extent the axonost (Ax.). The articular surfaces 

 bear pads of a peculiar kind of soft cartilage (M.C.). Each 

 half of the fin ray is connected with the baseost by a stout 

 ligament (F.R. d). Now the only connection between the 



f Whatever doubts may arise on this point will be settled by a reference 

 to the condition in Solea, as described by Cunningham; and in Rhombus, 

 as described by Kyle. 



