GOBIOIDS. 
241 
The membrane that unites the two ventral fins, may 
sometimes be wanting in front; and Winther" attempted 
to make the presence or absence of this membrane a 
generic character. But as it may be wanting in spe- 
cimens of these species * 6 * * 9 perfectly typical in other re- 
spects, we can regard this only as an individual de- 
parture from the normal structure of the genus. 
One of the most remarkable peculiarities of this 
subfamily is the structure of the system of the lateral 
line. The system is not without the so-called muci- 
ferous ducts'. In Gobius niger for example, these ducts 
with their pores appear on the head, both in the hind 
margin of the preoperculum, on the parietal sides and 
the forehead (in a line from the upper corner of the 
branchial opening to the middle of the hind margin of 
the eye), between the eyes and on the snout, on the 
inner side of the nostrils. Solger 1 ', however, searched 
in vain for sensory organs in these ducts. On the 
other hand, the cheeks, the branches of the lower jaw, 
the gill-cover, the occiput, and one row of scales on 
the sides of the body or, at least, some of the scales 
in that row which corresponds to the lateral line, are 
furnished with external, small papillae, which have the 
appearance of sensory organs, and are arranged in more 
or less regular rows. The histological structure of 
these sensory organs, composed, as they are, partly of 
indifferent, epithelial cells and partly of pear-shaped, 
sensory cells, tipped with bristles, which project into 
the cupula covering the top of the organs and filling 
a cavity bare of epidermic cells, corresponds to the 
structure ascribed by F. E. Schultze' to the sensory 
organs of the lateral line proper and the other parts 
of this system. The position of these organs, which lie 
uncovered on the surface of the skin, represents the 
earlier developmental stages of the system of the lateral 
line, as Schultze has shown, before it is furnished 
with ducts, originally channelled, and at length perfected 
by the coalescence of the dermal folds which have risen 
on each side of the sensory organs already present. 
Similar free, “embryonal”, lateral organs also occur in 
the fry of the Pike and the Sticklebacks', and may 
perhaps be present in many other fishes, especially those 
in which the lateral line is indistinct or broken; but 
nowhere are they so distinct as in some members of 
the subfamily Gobiince. 
The generative organs of these fishes call for spe- 
cial attention. In the male of the Common Scandina- 
vian Goby ( Gobius niger), during the spawning-season, 
the testes are considerably expanded posteriorly, lobate 
Fig. 63. Dermal papillas on the head (magn. ly 2 diam.) and on two 
of the scales of the left lateral line (magn. 6 diam.) in Gobius niger. 
After Winther. 
and of a spongeous structure with relatively large 
meshes. The two hindmost lobes, one on each testis, 
or sometimes three — one of them in this case being 
unpaired, and issuing from the union of the vasa defe- 
rential or belonging to the left testis — issue from 
the testes proper in the form of flat, triangular disks 
with rounded corners, which are considerably broader 
and even thicker than the latter, but like them open 
into the vasa defer entia. Rathke described them 6 
under the name of auxiliary generative organs, and ex- 
plained their function partly as prostatic formations, 
a Naturh. Tidskr. Kbhvn, ser. 3, vol. XI, p. 49. 
6 In a Gobius pictus (Auctt.) from Allinge (Bornholm) the membrane which in other cases unites the ventral fins, is so small and 
thin, that it was only after the minutest examination that we could find any traces of it. 
c Of. Cuv., Val., Hist. Nat. Poiss., vol. XII, pp. 33 and 87; Winther, Naturb. Tidskr. Kbhvn, ser. 3, vol. IX, p. 181, plate VII. 
d Arch. Mikr. Anat., Bd. XVIII (1880), p. 377. 
e Arch. Mikr. Anat, Bd. VI (1870), pp. 62 etc., plates IV — VI. 
z Leydig, Neue Beitr. Anat. Kenntn. d. HautdecJce und Hautsinnesorgane der Fische , Festschr. z. Feier d. Hundertj. Best. d. Naturf. 
Gesellsch. in Halle a /S, 1879. See also Solger, 1. c. 
9 According to Rathke. 
h Fiber den Darmkanal und die Zeugungsorgane der Fische , p. 201, tab. V, fig. 9 — 11, in Beitr. z. Gesch. d. Tliierwelt, Abth. 2 
(Scbr. Naturf. Ges. Danzig, Heft. Ill, 1824). Of. also Kroyer, Damn. Fiske, vol. I, p. 395. 
Scandinavian Fishes. 
31 
