SUBJECT INDEX — MORPHOLOGICAL SECTION 



399' 



Anarrhichas and Chcetodon. Andr6, AA'. 

 1784.1. —Scaridm. •Boas, J. E. 1879.2. 



— Orthagoriscus. Hilgendorf, F. M. 

 1893.1. — Salmo7iidcE. Knox, R. 1855.1. 



— Echeneis. Mummery, J. H. 1899.1; 

 Murray, A. 1S56. 1 . — Gyninodonies. 

 Owen, R. 1839.4, 1S40.3. — Piabuca. 

 Rowntree, W. S. 1906.1. — Cyclopterus. 

 •Schmidt, B. 1913.1. —Esox, Tomes, 

 C. S. 1878.1. —Mugil. Troschel, F. H. 



1865.1. — Loricariidce. Weyenbergh, H. 



1875.2. — Anarrhichas. Wilson, A. 

 1879.1, .2. —Labrus. Wright. J. 1870.1. 

 — Hydrocyon. Eastman, C.R. Add. 1917.1. 



Although Coregonus ivarimanni is tooth- 

 less when adult, true rudimentary teeth 

 occur in embryos of 1 cm. Walter, H. E. 

 1894.1. 



Pharyngeal teeth of Teleostei 



In certain Teleosts occur clusters of grinding 

 teeth (pharyngeal teeth) capable of replacement 

 by vertical succession. 



The lower pharyngeals are usually composed 

 of the paired ceratobranchial elements of the 

 last (fifth) branchial arch which is reduced on 

 each side to this element. 



In the Cyprinidse these grind against a callous 

 pad above on the basi-occipital. 



In the Labridae they are opposed above by the 

 upper pharyngeal teeth formed on the pharyngo- 

 branchials of the posterior branchial arches. 



For an excellent series, ivith photographs, 

 of the pharyngeal teeth of many different 

 species, see •Shepherd, C E. 1913.1^. 



Pharyngeal teeth of Cyprinidoe. (5erka- 

 sov, P. G. 1903.1; Faek, - 1897.1; • Gra- 

 cianov, V. 1. 1900.1; •HaempeikO. 1907.2, 

 1908.2,-3; Hoppe, R. 1894.1; Jurine, L. 

 1821.2; Leonhardt,E. E. 1903.10; Molin, 

 R. 1850.1; Nordmami, A. 1863.2. 



Variability of pharyngeal teeth in Cy- 

 prinoid hybrids. Heincke, F. 1892.1. 



Pharyngeal teeth of other fishes. — 

 Scaridce. Boas, J. E. 1879.2. — Labridce, 

 development. Prince, E. E. 1893.1. ~ 

 Orestias. Pellegrin, J. 1904.12. — Ger~ 

 ridcE. Sauvage, H. E. 1876.4. — Labrus. 

 Wright, J. 1870.1. 



Comparison of pharyngeals of Labrus 

 from Italian Tertiary with those of recent 

 Mediterranean species. Bninati, R. 1909.1. 



Isolated fossil or sub-fossil pharyngeal 

 teeth were earlier known as "Serpent's 

 eyes.'' See Jussieu, A. Pre-Linn. 1725.1. 



DERMAL SKELETON (OF FISHES) 



Comprising the morpholog'y of the Exo- 

 skeleton, the Dermal Denticles, and the 

 Scales. 



The dermal fin-rays (dermotrichia) , which 

 constitute a part of the exoskeleton, are treated 

 under Fins. 



The dermal skeleton should properly include 

 the " dermal " or " membrane bones," but these 

 are necessarily treated under Skull. 



Scales are usually included under the general 

 term *' integumenti" In the present work, how- 

 ever, under Integument, will be found references 

 merely to the soft structures of the epidermis 

 and the dermis. 



Introductory 



In the Cyclostomata the skin is soft and en- 

 tirely lacking in hard structures such as den- 

 ticles or scales. There is thus no suggestion of 

 a dermal skeleton in this group. 



In the Elasmobranchs, however, true " pla- 

 coid " denticles are present. These, more fully 

 described below, consist of separate hollow 

 cones of dentine capped by " enamel." Each 

 separate denticle, with growth, develops a more 

 or less expanded basal portion, the " basal 

 plate," In these fishes, true bone never de- 

 velops. 



In the higher bony-fishes (Teleostomes) and 

 in the Dipnoi the true scales occur. These 

 develop, usually as oval flattened structures, 

 in pockets within the dermis and are at no 

 time contributed to by the epidermis. They 

 grow throughout life by the deposition of 

 successive layers of bony substance . 



Agassiz (J, L. 1833,'2) divided fishes into the 

 four groups, Placoidei, Ganoidei, Cycloidei, 

 and Ctepoidei, based on the characters of their 

 scales. That this arrangement was untenable, 

 especially for the higher groups, was soon shown 

 by the experience of one of his students. Prof.. 

 N. S. Shaler (Atlantic Monthly, Feb.^, 1909, 

 p. 222), who discovered that one species of Pleu- 

 ronectidse " had cycloid scales on one side and 

 ctenoid on the other." Likewise Peters (W. C. 

 H. 1841.1) soon showed that the bonito (Sarda) 

 possesses both cycloid and ctenoid scales.. 

 Agassiz (1850.6) decided that the scales of the 

 bonito were intermediate and sometime later 

 (1857.2) he definitely renounced his classifica- 

 tion as being too artificial. 



Except among palseontologists. where often 

 the scales of certain fossil forms constitute the 

 only remains preserved, the scales have not. 

 been much studied as an aid in the classifica- 

 tion of fishes. 



More recently Cockerell (T. D. 1909.4- 

 1914.1) has assiduously studied and described 

 the minute structure of the scales of many 

 species in all groups, especially the Teleostomes,. 

 with the idea of defining the distinctive char- 

 acters which may aid in the determination or 

 identification of the species. The taxonomic 

 value of " lepidology " has however not since 

 been extended. 



Principal literature 



Modern views on the morphology and de- 

 velopment of scales had their inception in 

 the works cited under -*■ Williamson, W. C. 

 1849.1, and 1851.1. 



The most comprehensive treatises in 

 German, on the morphology of dermal ' 

 (placoid) denticles and scales are -A-Hert- 

 wig, 0. 1876.1; and •Klaatsch, H. 1890.1. 



By far the most illuminative memoir {in 

 English) on the development, structure, and' 

 phylogeny of denticles and scales is :A"Good- 

 rich, E. S. 1908.1. 



Most of the previous views on the de- 

 velopment and formation of scales are ■ 

 reviewed in English in It Thomson, J. S. 

 1904.1. 



As stated above, Cockerell (T. D. 1909.4- 

 1914.1, Add. 1914.1) has described the 

 superficial characters of the scales of many 

 genera and species of fishes. See especially ■ 

 •Cockerell, T. D. 1911.5 and 1913.1. 



Miscellaneous papers 



Mechanical considerations of the evolu- 

 tion, or causes of the arrangement and 

 shape of scales. Ryder, J. A. 1892.1; 

 AVoodward, A. S. 1893.5. 



Older or miscellaneous and unimportant 

 papers on the structure and manner of 

 growth of the scales of fishes. Agassiz, J. 

 L. 1840. 2, .3, .4; Alessandrini, A. 1849.1;, 



