826 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [80 j 



obtains also in the Mudfish. Here, too, the rays, if maceration is car- 

 ried to excess, cleave in twain longitudinally, but as this can be studied 

 to better advantage in the caudal rays of this Ganoid, I defer saying 

 anything more about it until that part comes to be described. 



lu Micropterus the apex of the united pelvic bones are inserted pos- 

 teriorly into the angle formed by the articulation of the proscapulse. 

 The pelvic bones are situated, as we shall see further on, far back in 

 Amia, and dift'er very much in their general character. . 



Upon the outer side of each proscapula in Amia are found a pair of 

 very curious-appearing scales, composed apparently .of a toughened 

 membrane, marked in an irregular manner by lines of semi-osseous 

 material, that require the aid of a lens to properly study. These pecu- 

 liar affairs are attached loosely to the sides of the proscapulse, but up 

 to the present writing I am not aware that any physiologist has ad- 

 vanced a theory as to the original function of these appendages. They 

 have no evident use now. In referring to these interesting structures, 

 Dr. Wilder says that^* " upon each side of the copula, or isthmus, which 

 connects the shoulder-girdle of Amia^^ with the hyoid arch, there are 

 two appendages which are rarely mentioned by authors, and whose 

 nature appears to be undetermined." "^ 



^^ Historical sketch. — According to Dum6ril,^^ these appendages are what 

 Linnaeus referred to in the following jjhrase, to which zoologists who 

 have spoken of Amia do not appear to have attached a detinite sig- 

 nificance: Gula ossiculis, scutiformibus, e centro striatus. Valenciennes 

 supposed that he was impressed by the appearance of the branchioste- 

 gal rays, which form on each side a sort of striated plate ; but in the 

 phrase cited reference is evidently made to the two small dentated 

 pieces of which I am speaking, and which is easy to see. I have also 

 found them mentioned by JStannius." With further quotation from 

 Dumeril, the doctor says, " The appendages are not mentioned in 

 Franque's description of Amia, nor in the monographs or systematic 



fi* Wilder, Burt Gr., on the Serrated Appendages of the Throat of Amia, Proc. Amer. 

 Assn. of Science, 1876, page 259. 



® Amia is a iish found living in the Mississippi River and its tributaries, and in the 

 great lakes. It attains a length of two feet, and is called by fishermen "mudfish," 

 "dogfish," and "lake-lawyer." Under the tip of the lower jaw is a movable plate, 

 which does not exist in any other fresh- water fish of America. The adult male has a 

 circular dark spot at the base of the tail (Jordan, 23, 306). Amia is now usually re- 

 garded as a ganoid, and its brain closely resembles that of Lepidosteus (the gar- 

 pike); but it seems to be, as remarked by Gill (10), the "most teleosteoid" of that 

 group. [This foot-note is from Dr. Wilder's article. ] 



661 regret to say that it proved to be impracticable to reproduce Dr. Wilder's figures 

 in his very instructive plate. 



^' I have omitted, in this long but important quotation from Wilder's paper, the 

 figures which this author gives that refer to the bibliographical table at the end of 

 his article. Those who wish to refer to the authorities quoted will have to turn to 

 the Proceedings containing this list. So short is Dr. Wilder's paper, and j'et his ob- 

 servations are so valuable iu the present connection, that I have incorporated them 

 quite extensively, a fact that the reader no doubt will appreciate. 



