THE SHOULDER-GIRDLE IN FISHES. 15 



fig. 16, but the letters sc. are wrongly put to the bone below it. In fig. 17 it is marked x and sc., 

 and it is largely overlapped by the operculum (Op.} and in its turn overlaps the bone below it; it 

 is not the scapula, but a subcutaneous bone, the " supra-clavicle." The bone below, which passes 

 obliquely inside the base of the last, is the true clavicle ; it is marked C, meaning that it is Owen's 

 " coracoid : " it is subcutaneous, like the last ; is broad at the top, and pinched at the middle ; and 

 lower down it broadens, passes inwards, becomes blunt-pointed, and is separated from its fellow 

 by about 3 lines. On its inside, its middle third is in relation with the Shoulder-girdle proper (fig. 

 17, 1.), which is very small, but is ossified. The lower bone (fig. 17, C l ) does meet its fellow, 

 and it is formed by the ossification of a more external part of the skin ; it overlaps the base of 

 the clavicle, underlying it, and passing mesiad to meet its fellow : this is the " interclavicle." 

 Now, we saw that in the Sturgeon the four dermal additions to the Shoulder-girdle moiety had 

 all more or less of the ganoid surface besides the subcutaneous laminae, and that the second 

 of these the " supra-clavicle " (see Plate I, figs. 6 and 8, s. cl.) had very little ; so now we 

 see in the Polypterus, which comes much nearer th e Teleostei, that only the uppermost and the 

 lowest of these bones retain the ganoid surface. In the Sturgeon the lowest overlaps the one 

 above it, and yet is in relation with the soft " epicoracoid" (see Plate I, figs. 6 8, e. cr., cl., i. cl.). 

 But Muller's figure shows another plate (marked^ in fig. 17) ; it is overlapped by the supra- 

 clavicle (of) in front, and by the clavicle (C.) below. If the reader will refer to Professor Hyrtl's 

 preparation in the Hunterian Museum, he will see another plate, which lies behind and within 

 the one in question ; this last is the " lower post-clavicle," and the bone y is the " upper post- 

 clavicle/' Now, if we turn to the large skeleton of Polypterus SicMr (marked " 327 B ") we shall 

 see three succeeding vertical rows of such bones: the first row only comes under my nomenclature. 

 The uppermost of this first row is the bone which next succeeds to the so-called " supra-scapula," 

 or the " post-temporal : " its true counterpart is the second " lateral-line " bone of the Teleostei 

 (see Plate II, fig. 12, 1.1. 2): the middle and lower bones are the "upper" and "lower 

 post-clavicles." Fig. 17 of Professor Huxley's Memoir has the coracoid marked 1; the 

 scapula, above it, is not lettered. These bones are also figured in Professor Owen's ' Lectures' 

 (1846, Vol. 2, p. 122, fig. 41); here 54 is, in miy opinion, the scapula, and 55 the coracoid. 

 Referring to the skeletons we find that the whole moiety of the Shoulder-girdle is a small semi- 

 lunar plate deeply notched in front (this is the " coraco-s capular notch"), and having one bony 

 centre for the scapula, and one for the coracoid : the w hole of this plate is too small to reach 

 either the "supra-clavicle" above, or the " inter-clavicle" below ; it lies inside the middle third 

 of the clavicle. 



Example 2. Calamoichtliys calabaricus, J. A. Smith. 





Since the above was written I have been able to obtain a specimen of this newly dis- 

 covered Ganoid Fish (a sub-generic form of Polypterus) from Old Calabar. In the ' Annals 

 and Magazine of Natural History' for August, 1866, pp. 112 114, there is a description of this 

 Fish by Dr. J. Alex. Smith, with remarks upon its internal structure by Dr. Traquair. 1 



The woodcuts (p. 16, figs. 1 A, 1 B, 1 C) show the part of this Fish's structure with which I have 

 to deal : fig. 1, A and B, magnified five diameters, and fig. 1 C, ten diameters : the entire specimen 

 measures 8J inches in length. The three upper dermal shoulder-plates (fig. 1 A, p. t., s. cl., cl.) 



1 Communicated by Dr. Smith, from the ' Proceedings of the Royal Society of Edinburgh.' 



