440 MR. F. E. BEDDARD ON THE [JunC 3, 



Not much, as it appears to me, can be gathered from the above 

 facts as to the relationship of Por^ica : it is not distinctive! j' llalline 

 nor is it, on the other hand, distinctively Colymbiue. In Porzana and 

 Gallinula (Giebel) there is a fusion between a number of the dorsal 

 vertebrae. 



The coracoiclis a stout bone ; the mesocoracoid process (Parker, 11) 

 is continued into a long thin ridge, -which extends along nearly the 

 whole of the inner edge of the bone, gradually decreasing in depth. 



This process is much larger than in any Eail which I have 

 examined, but not so large as in PsopMa (cf. P. Z. S. 1890, p. 33G). 

 In the Grebes the process in question is obsolete or rudimentary. 



The clavicle has been already partly described in connection with 

 the sternum ; it is attached above to the mesocoracoid process and to 

 the acromion. In Heliornis the furcula is also firmly attached to the 

 carina sterni, but Giebel has omitted to mention anything about the 

 anterior and posterior interclavicular processes. The articulation of 

 the clavicle is a point upon which Fiirbringer lays some importance ; 

 it aUics Podica with the Hails and not with the Divers, in which 

 birds the clavicle extends beyond the acromion. 



The Heliornithidoi thus agree with the Rails in the following 

 characters : — 



(1) In the general structure of the skull. 



(2) In the general form of the pelvis. 



(3) In the pterylosis. 



(4) In the presence of an expansor secondariorum and in the re- 

 lation of the tendons of this muscle. 



They agree with the Cohjmhidce in the following : — 



(1) The insertion of the bicejjs slip on to the patagium instead 

 of on to the tendon of the ixitiuiialh lonr/us. 



(2) In the characters of the latissimi dorsi. 



(3) In the muscle-formula of the leg, which is ABX-i- (with 

 Colymbus, not with Podiceps). 



The HeliornithidcB appear to be peculiar in the following charac- 

 ters : — 



(1) The absence of an aftershaft. 



(2) The form of the sternum. 



(3) The shape and relations of the interclavicular '. 



(4) In the fusion of the pubes with the ischia and the absence of 

 lateral postacetabular ridges. 



(5) In the arrangement of the intestinal coils. 



(6) In the form of the biceps cruris. 



It will be evident therefore, from a glance at the above statement, 

 that the JMiornitJiidn' have more characters peculiar to themselves 

 than characters which all}' them with either the llalline or Colymbiue 

 birds ; and these characters appear to me to be not merely numerous 

 but also for the most part important ones : nor are they confined 



' I do nut oiiipli;isize the resemblances which they show in tliis or other par- 

 ticulars to other groups of birds. 



