OSTKOLOGY, ETC., OP STNGNATHUS PECKIANUS. 635 



The only literature referring in any important way to the 

 development of the Lophobranchii which I have been able 

 to find is confined to three papers; of these, Calberla-'s^ treats 

 of a much earlier stage than I have been able to study, and 

 (le Quatrefages'^ is of little or no importance, leaving only J. A. 

 llyder's^ from which I could obtain any information Dr. 

 Kyder's observations were unfortunately limited to a single 

 specimen of Hippocampus antiquorum, which had just 

 left the brood-pouch, and corresponds almost to my Stage d, 

 being very slightly older. From the rather peculiar arrange- 

 ment of the mandibular skeleton at this stage no little difficulty 

 would no doubt be experienced in determining the homologies 

 of the cartilages from a single specimen, since it is only by 

 tracing their development that one can be certain of the signi- 

 fication of abnormalities. Accordingly, in Ryder's paper, there 

 are certain statements which I am convinced are errors, partly 

 of observation and partly of mistaken homology. 



These remarks apply especially to his description of the 

 mandibular and hyoid arches. On comparing Dr. Ryder's 

 figure with my drawing of the cartilages in Stage c (fig. 5) it 

 will be seen that what I have represented merely as a foramen 

 in the hyomandibular portion of the second postoral arch is in 

 his figure pourtrayed as a dividing line, completely separating 

 the hyomandibular cartilage into two parallel portions, the an- 

 terior of which he terms the metapterygoid. He was dealing 

 with Hippocampus a nti quorum, while my observations 

 were made on Syngnathus; but these two forms are very 

 closely allied, and the arrangement of the cartilages are appa- 

 rently identical, so that a statement made regarding one is no 

 doubt tenable for the other. Accordingly, since the develop- 



1 E. Calberla, " Zur Entw. des Medullarrohres u. d. Chorda dorsalis der 

 Teleostier u. d. Petrornvzouten," ' Morph. Jalirb.,' iii, 1879. 



^ A. de Quatrefages, " Memoire sur les Syngnathus," ' Ann. des Sci. Nat..' 

 1842. 



' J. A. Kyder, " A Contribution to the Development and Morphology of 

 the Lophobranchiates (Hippocampus auliquorum, the Sea Horse)," 

 ' Uull. U.S. Eish Comm.; Is81. 



