1012 



SCANDINAVIAN KISHES. 



and has the tonii of a flatteiiud cone. Higli up on ihc 

 superioi- arms of tlie clav icles ai-e attached the scapular 

 disks. These ai'e thin and in great part cartilaginous, 

 each con.si.sting of a circular scapular p;irt (fig. 265, sc), 

 witli an angular incision above and a small, round hole 

 (scapular fenestra) below, and a semicircular coracoid 

 part (tig. ■2(3.5. cr), both of tlieni litted into the mem- 

 brano-cartilaginous disk. A scapular disk as simple as 

 this belongs to the earliest stages of development in 

 other Teleosts; Init a manifest relic of the morphological 

 alliance witii more jjrimitive piscine types appears in 

 the great number of supporting Ijones (brachial bones 

 — fig. 265, h) possessed bj* the pectoral fins of the Eels. 

 In almost all" the preceding Teleosts the number has 

 been 4; in nur conininn I^el it is 7 uv 8. Amid, a Gan- 



thc primitive forms. Tlie loss of tlic ventral fins, on the 

 other hand, as we have seen in many of the preceding Te- 

 leosts, is, here too, .secondary in its significance; and in 

 foreign 1-^els the pectoral fins may share the same fate'. 

 The skeleton of an adult Eel is firmly ossified, and 

 characterised b}* its numerous vertebne — generally 

 more tlian 100, sometimes about 160 — of almost uni- 

 form shape and with feebly developed appendages. In 

 our common Eel the anterior vei'tebrie, to the seventh 

 inclusive, have their shallow but long, almost contiguous 

 neural spines broken up into several (as many as !•) 

 spicules''. The said vertebrae are furnished botli witii 

 upper" and lower' transverse processes. The former are 

 alary spines, directed backwards and of fairly uniform 

 strength, whicli are, liowever, exchanged on the seventli 



Fig. 2U(). Three iiliddiniiial vertebra? (44 — 46) in Anrjiiilla viilrjaris, seen from the left and magnified. 



j/a, scleral bone (ei)ineiiral, cf. fig. 23G, \>. 947); psps, iijijier spinous process; ptrp, lower posterior transverse process (processus transversus 



posterior); ptra, lower anterior trimsversc ]irocess; Ini. li;em;d arch; pspt, lower siiinoiis process (processus spiiiosus inferior); pi, ribs. 



oid genus, lias the same number; and rahiptcnis. an- 

 othei- Ganoid genus, has 13 — 1? brachial l)ones. These 

 Ganoids have besides retained one or more bones be- 

 longing to the innermost (proximal) row of tlie prim- 

 ordial cartilage (Gegenbauk's pterygium) of the pectoral 

 fins, which has entirely disappeai-ed in the Teleosts. 

 During the evolution of the Teleost type the basal parts 

 of the pectoral fins have thus suffered reduction''; and 

 the Eels are most nearly approximated in this respect to 



and following vertebra' for sclernl bones, directed back- 

 wards and upwards in the dorsal half of the great lateral 

 muscle (fig. 266, no). The lower transverse processes 

 {ptra) of the first \ertebra are only small, pointed [jro- 

 tuberances. C)n the following vertebrip they grow 

 broader, but from the seventh vertebra inclusive they 

 become pointed s[>ines, directed outwards, backwards, 

 and downwards, and bearing at the tips short and \\eak 

 ribs {pJ), which in their turn give place towards the 



" For exceptions see the Italraehoids (p. 133, aliove) and tlie Lopbioids (p. 13G). Ostracion, a Pleclognalc, has .0 liasal tiones. 



' Cf. Smitt, Ur de hiigre djvrens iitvechlingshistoria, p)). 222 seq(|. 



'' Cf. the Lophobranchs, see above, pp. 667 seqq. 



'' In the Conger this division is restrieteil to llie formation of lateral grooves on the neural spines, li\it is peri'eplible in tliis form 

 vcn in the 13th vertebra. 



' Diapopliyses. 



f Parapophyses. 



