1014 



SCAXDIXAVIAN FISHES. 



include witliin tlicir flcjveii base tlie iiiargiu uf the 

 hypural bones and urostyle. Tlie spinal canal extends 

 straight l)ack towards the end of the last Aertebra (f), 

 the body of which is compressed to form the urostyle 

 (.!■), also directed straight backwards. The first (posterior) 

 hypural bone (li) is really composed, in analogy to the 

 primordial continence of the last two vertebra-, of two 

 luemal jiarts, \\hich have been united in an arch at the 

 base (proximally), just below the last vertebra, and have 

 closely applied their outer (distal) extremities to each 



other, thus including an elliptical cavity', in \vhich the 

 pulsating lymph-heai-t of the Eels is situated". The 

 lower (anterior) lnj)ural bone (between j) and r) an- 

 swers to the ha-mal spine of the penultimate vertebra, 

 which also supports the hindmost hasmal arch (j>). In 

 young Eels, as well as in the Conger, Robin found this 

 hypural bone to lie fairly well developed'' and originally 

 divided by a suture from the hannal arch. In older 

 Eels (lig. 267, 7^) it is extremely narrow, and lies, in 

 the form of an osseous rod, close to the under mar<nn 



squ s,.li. 



spKo j' s,u 





?'r spt,, 



D 



Fig. 268. Skull of an AnguiUa vulgarifi. ^ ., linies the natiirnl sizi'. A: witli branchial apparatus, jaw-bones, and orl)it. B: cranium, seen 



from above. C: the same, from the riglit; D: tlie same, from below; E: the same, from behind. 

 al.sp, alisphenoid; bo, basilar jiart of the occipital; et, etv, and v, ethmoid (el) and vomer (v), conflvient in front; fr, frontal; '"". hyomandi- 

 bular; iojj, interoperculum ; /, lingual; lo, lateral parts of the occipital; mdh, mandible; 7nt, mastoid part of the temporal; op, operculum; par, 

 parietal; po/i, preorbital: pop, preopcrcnlum ; psp, parasphenoid ; ptr, petrosal; <ju, quadrate; /?. br., branchiostegal rays; xo, squamosal part of 

 tlie occipital; sob, liindmost part of the suliorliital ring; sop, suboperculum ; spet, supraethmoidal; ^plio, postf rental (sphenotic); fjti. s(|uimiosal 



part of the temporal; ;//;, urohj'oid. 



" In the Conger tlie ujijier (]iosterior) part of this liypural bone coalesces with the lower edge of tlie urostyle. See Robin, Joum. 

 Anat., Phys. 1880, jd. XXV, figs. 1 and 2. 



' Cf. KOBIN, 1. c., pi. XXV, fig. 3 and pi. XXIV, fig. 4. 



