EEL-FISHES. 
1013 
tail to scleral bones in the ventral half of the lateral 
muscle. Throughout the greater part of the abdominal 
region, from the 8th vertebra to the 44th inclusive, we 
find in the common Eel another pair of lower transverse 
processes (parapophyses, ptrp), behind the last-mentioned 
processes and always smaller than these. On the 45th 
vertebra, or sometimes on the 44th, this posterior trans- 
verse process on each side of the bone disappears, or 
is at least reduced more perceptibly than before; but 
the anterior transverse process divides instead into two 
(three) branches,' the anterior (outer) supporting the 
rib, the posterior (ha), which is simple or double, curv- 
ing inwards. On the 46th vertebra this posterior 
branch springing from one side of the vertebra joins 
the corresponding branch of the other side, to form 
(an inner) transverse process, the former continued by 
a row of transverse processes at the middle of the 
sides of the caudal vertebrae (which row is wanting in 
the common Eel), the latter by the row which curves 
downwards and inwards to form the haemal canal of 
the caudal region. The skeleton of the Eel, for all its 
simplicity, thus shows with the greatest distinctness how 
the vertebral appendages may be homologous in the 
lower grades of differentiation, although, when the 
differentiation is more advanced, they are different 
both in origin and functions. 
The tip of the tail presents the appearance of a 
rather primitive (diphycercal) structure. Only the outer- 
most (last) two vertebral — the outermost of which is 
composed, at least in our common Eel, of two prim- 
U t 
Fig. 267. Skeletal parts of the tip of the , tail in Anguilla vulgaris , seen from the left side and magnified. 
A: from a young Eel (Elver, Fr. Uivelle ), after Robin; B: from a full-grown Eel. 
v, vertebra, originally the antepenultimate, subsequently the penultimate; p, its h temal arch; n, its neural arch; »>,, its spinal canal; u, origi- 
nally penultimate vertebra, afterwards confluent with the last vertebra; i, primordial articulation between these vertebra*; h, hindmost haemal 
arches, surrounding the cavity of the lymph-heart; £, termination of the spinal canal; r , lowest, s, uppermost ray of the caudal fin; 
w, posterior expansion of the urostyle. 
the closed htemal arch and its hannal spine ( pspi ). In 
the Conger the said posterior parapophysis appears only 
on a few vertebral in the hindmost part of the ab- 
dominal region, and even there is not always present, 
or is sometimes developed only on one side of the ver- 
tebra?. But the parapophyses of the abdominal vertebra? 
are broad, as in the Codfishes, and pierced at the base"; 
and in the last 9 or 10 abdominal vertebra? the anterior 
parapophysis divides into an upper (outer) and a. lower 
ordial vertebra? — enter into the structure of the appa- 
ratus supporting the caudal tin. Although the vertical 
tins of the Eels are, as a rule 6 , so confluent that no 
separate caudal fin can be distinguished externally, the 
presence of such a fin is indicated internally by the 
circumstance that the hindmost fin-rays — 10, both in 
our common Eel (fig. 267, r — s ) and in the Conger 0 — 
do not articulate like the others by means of a flat ar- 
ticulary surface with separate interspinal bones, but 
a In the Murasna the posterior parapophysis divides on the 25th vertebra, and from, the 73rd vertebra. inclusive its lower branch enters 
into the structure of the closed haemal arch: — see Owen, Anat. Physiol. Vertebr., vol. I, p. 45. 
* In some, however, as in Ophichthys , the tip of the tail is free, without any trace of caudal fin. 
c In the Murrena 6. 
