362 



AMERICAN MUSEUM OF NATURAL HISTORY 



Abdominal Pores — Cont'd. 



In the lamprey {Petromyzon), in which 

 the eggs are small, there is a pair of small 

 . pores opening into an urogenital sinus. 

 Ewart, J. C. 1876.1. 



In the Myxinoids, which have large eggs, 

 Myxine possesses a single, median pore, 

 of very considerable size, opening into a 

 cloacal chamber, while Bdellostoma has 

 an enormous pore divided into two. -(^Burne, 

 R. H. 1898.1. 



Abdominal pores of Elasmobranchii 



Abdominal pores are usually present in this 

 group, but are subject to considerable varia-. 

 tion, being often present on one side while ab- 

 sent on the other. The Cestraciontidje and 

 RhinidEe lack them entirely. In other forms 

 (Scyllium stellare, S. canicula, Pristiurus melanos- 

 tomus, Spinax niger), they appear only at sexual 

 maturity and may in certain individuals be 

 absent. 



A table showing their distribution ap- 

 pears in -kBles, E. J. 1898.2. 



Other papers of lesser importance re- 

 lating to the abdominal pores of sharks 

 are Bridge, T. W. 1879.1; Howes, 

 G. B. 1890.3; Schneider, G. 1897.1; and 

 Turner, W. 1879.1. 



Abdominal pores in Teleostomi 



The distribution of abdominal pores in this 

 group, together with the literature, is fully given 

 by Bles (E. J. 1898.1). 



The Crossopterygii possess them as demon- 

 strated in Polypterus by Hyrtl, and in Cala- 

 moichihys by Bridge. 



The Chondrostei; Polyodon has abdominal 

 pores (A; Wagner, and Hyrtl) ; while practi- 

 cally all species of Acipenser have them (Johannes 

 Muller, Hyrtl, and Stannius) . 



The Holostei: " Amia calva — This fish was 

 carefully examined by Hyrtl, and at first with- 

 out success, for the presence of abdominal pores. 

 He discovered them in a large specimen as very 

 fine canals . . . Bridge confirms Hyrtl's ob- 

 servations, adding that the pores are open in 

 both sexes." 



*^ Lepidosteus osseus finally, like all other 

 known Ganoids, has abdominal pores. They 

 were described and figured by Hyrtl and men- 

 tioned by Bridge, but were first discovered by 

 Joh. Muller." (Bles, E. J. 1898.1, p. 502.) 



Various papers on the abdorriinal pores 

 of the Teleostomes, are Ayers, H. 1884.1; 

 Hyrtl, C.J. 1852.1, 1854.2; and lonescu, 

 C. N. 1905.1. 



Abdominal pores of Dipnoi 

 " According to Hyrtl, Lepidosiren paradoxa, 

 Fitz., has no peritoneal canals or abdominal 

 pores: and Bischoff [T. L. 1840.1] . . . makes 

 no mention of such openings. Ceratodus, on 

 the other hand is well known to have pores, as 

 first described by Giinther [A. C. 1871.4], paired 

 and opening behind the cloaca. 



"... P[rotopterus] annectens . . . has ab- 

 dominal pores." Bles, E. J. 1898.1, p. 504. 



ADAPTATIONS 



See also Ecology, Evolution, etc. 



For adaptations to varying saline content of 

 water; adaptations of freshwater fishes to sea- 

 water and vice versa, see under Physiology. 



For adaptation of coloration to surroundings, 

 see under Coloration: in form or shape of fishes, 

 see under Form. 



For adaptations to their peculiar habitat and 

 manner, of life, see Blind Fishes of the Caves, 

 Deep Sea Fishes, and Pelagic Fishes. 



Generalia. Agassiz, J. L. 1854.4; Baird, 

 S. F. 1871.47; •Eigenmann, C. H. 1909.1 

 (Address); Fatio, V. 1904.1, 1905.1; 

 Nichols, J. T. 1915.1,.7; Osburn, R. C. 

 1911.11; Prince, E. E. 1901.1. 



Adaptations to an aquatic habitat. Abel, 

 O. 1905.1. — To terrestrial existence. 

 Cu6not, L. 1895.1. — Deep-sea fishes. 

 Delaroche, F. E. 1809.3. — Adaptations of 

 sailfishes to a pelagic life. DoUo, L. 1909.5. 

 — Adaptations illustrating " habitus " and 

 " heritage." Gregory, W. K. & Adams, 

 L. A. 1914.1. — Sagittiform structure of 

 nectonic fishes. Schlesinger, G. 1909.1. 



Adaptations of Scomberesocidoe to a 

 pelagic manner of life. Schlesinger, G. 

 1909.2. — Adaptations of Mormyridm to 

 manner of food gathering. Schlesinger, G. 

 1910. 2, .4. — Adaptation of Gobiidce to a 

 planktonic life. Brunelli, G. & Atella, E. 

 Add. 19141. 



Adaptations of fossil fishes to their man- 

 ner of life. •DoUo, L. 1909.4; Abel, O. 

 Add. 1914.1. 



ADHESIVE DISK 



General treatise on the adhesive disk of 

 fishes. -y^Niemiec, J. 1885.1. 



Fixation against the current by means of 

 spines acting as adhesive organs. Thilo, O. 

 1900.1,.2, 1903.1. 



Disk formed through a modification of 

 the dorsal fin. — In Echeneis. Beck, G. 

 1879.1; Cope, E. D. 1889.4; Home, E. 

 1816.1; •Houy, R. 1909.1; Storms, R. 

 1888.1; Townsend, C. H. 1915.1. — 

 Fossil showing disk. Wettstein, A. 1886.1. 



InRemora. Baudelot,E. 1867.3; Blain- 

 ville, H. IVl. 1822.2; Kner, R. 1860.2. 



Disk formed by the united ventral fins. 

 In — Cyclopterus. Baudelot, E. 1868.7 

 Borckert, H. 1889.1; •Guitel, F. 1891.3 

 1896.1. — Liparis. Reicher, E. 1913.1 

 Stuckens, M. 1884.1; Smith, W. A. Add 

 1885.1. — Lepadogaster. Fiebiger, J. 1905. 1 

 Smith, W. A. Add. 1885.1. 



ADHESIVE OR CEMENT ORGANS 



Transient larval organs, situated as a 

 crescent-shaped median furro\if or a pair of 

 knobs near _ the mouth, being glandular and 

 serving to aid in the attachment or cementing 

 to surroundings of the larval fishes. 



In Amia, as first pointed out by Reighard 

 and Phelps (1908.1), these are of endodermal 

 origin arising in the form of pockets which later, 

 however, separate and fuse with the ectoderm. 

 By them, they were homologized with the an- 

 terior pair of head cavities of Elasmobranchs. 

 Kerr (J. G. 1906.1) has suggested their possi- 

 ble correspondence with the premandibular 

 head cavities of higher vertebrates. 



In Dipnoi (Protopterus and Lepidosiren), 

 and Amphibia, the cehient organs are apparently 

 of ectodermal origin, but Professor Kerr beUeves 

 that here the endodermal stages have been 

 eUminated from the embryonic development. 



Structure and development in — Pro- 

 topterus, Hyperopisus, and Sarcodaces. 



