SYNENTOGNATES. 
pseudorays on the hind margin, like the still more pro- 
minent growths in the Ganoid genus Polypterus. 
In the Synentognates the system of the lateral line 
is most highly developed in the lateral line itself, which 
is situated low down, and generally runs along a some- 
what elevated carina on each side of the belly from the 
lower anterior corner of the clavicular region to the base 
of the caudal fin, being more or less complete through- 
out its course. Sometimes, on the tail behind the anal 
fin, it curves upwards on a middle carina along each side 
of the body, and advances over the membrane between 
the middle rays of the caudal fin. However, the lateral 
line, as usual, originates in the temporal region, and a 
connective branch, which is often visible externally, runs 
downward behind the pectoral tin and joins the ventral 
branch below this point". The system of the lateral line 
on the head generally opens into a number of scattered, 
small, round pores on the posttemporal bone, the tem- 
poral region, anteriorly on the forehead above the eyes, 
sometimes out on the intermaxillary bones, when they 
are elongated, and also on the posterior and inferior 
margins of the preoperculum, from which point the row 
is continued on the branches of the lower jaw, when 
they are elongated. 
The ova of all these fishes, to the best of our know- 
ledge, are furnished with filaments on the shell 6 , like 
those we have noticed above in Gobius niger , but ar- 
ranged in a different manner, being scattered over the 
9 \ 9 
surface of the shell (tig. 91). By means of these fila- 
ments the eggs are united into clusters or attached to 
seaweed or other objects at the bottom of the sea, the 
■water in which they lie, being thus constantly changed 
by the ebb and flow of the tide. 
The Synentognates are active surface fishes, the 
great majority of them being pelagic; but some of them 
enter the lagoons, or, like several of the Mugiloids, 
Fig. 91. Egg of a Garpike enclosed in the shell, which is furnished 
with tentacular threads on the surface. The egg had undergone fer- 
tilization 3 h. 23 min. previously. Germinal disk (g) divided into 
8 segments. Magn. 1 1 l / 6 diam. After Ryder. 
ascend the rivers, or are even stationary fresh-water or 
brackish-water fishes. According to Gunther’s Catalogue 
about 180 species have been named, defined with more 
or less certainty and distributed among 5 genera. Gill 
and Bleeker have subsequently adopted 13 distinct 
genera for these forms. Most writers have included all 
the Synentognates in one single family, 
Fam. SCOMBRESOC1DJE, 
the characters of which thus coincide with 
On account of the difference in the jaw-teeth, how- 
ever, Gill 0 established two families: Belonidce , with 
sharp, sparse teeth, and Scombresocidce, with small jaw- 
teeth or destitute thereof. Bleeker (. Atl . Ichth.) adopted 
four subfamilies: Scombresoci formes, with both jaws 
elongated and with finlets behind the dorsal and anal 
fins; Mastacembeliformes , also with both jaws elongated, 
but without finlets; Hewiiramphiformes, with only the 
lower jaw elongated like a spear-head, the upper jaw 
forming a triangle in front of the snout proper; and 
those already given for the whole group. 
lastly, Exocoeti formes, with neither of the jaws elong- 
ated into a beak. The first three subfamilies are fur- 
ther distinguished from the fourth by the fact that in 
their case the maxillary bones are more or less firmly 
united to the lateral parts of the hind superior margin 
of the intermaxillary bones, in a manner winch calls 
to mind the structure of the Plectognates, thoug i here 
these bones may more easily be distinguished from each 
other, while the intermaxillary bones have a thin, but 
broad margin straight across the snout, and articulate 
“ We have not succeeded in finding a trace of the upper lateral line, which according to Valenciennes (Cuv., Val., Hist. Nat. Poiss., 
vol. XVIII, p. 406) and Bonaparte (Fn. Ital., tom. Ill, 2 — Pesci — Belone acus ) runs along the upper part of the sides of the body. 
Valenciennes states, however, that he has been able to trace the lateral nerve throughout the whole of its course. 
b ILeckel, Muller's Arch. f. Anat. 1855, p. 23, tafl. IV and V; Koi.liker, Verb. Phys., Med. Ges. Wiirzb., vol. VIII (1858), p. 80; 
Ryder, Bull. U. S. Fish. Comm., vol. I, p. 283, pi. XIX — XXI. 
c Arr. Fam. Fish., Smiths. Misc. Coll., No. 247, p. 14. 
