SUCKER-FISHES. 
407 
trunk vertebrae are extremely slender, the third alone being nearly as long as the 
whole caudal portion; while in the latter all the vertebrae are very short. In a 
fossil state the tortoise-fishes are represented in the middle Eocene of Monte Bolca; 
and it may be mentioned here that in the preceding family the genera Fistulciria 
and Aulostoma occur not only in those deposits, but likewise in the lower Eocene 
of Switzerland; and Auliscops has been recorded from the Eocene of Sumatra, 
and two extinct generic types have been described from the Monte Bolca beds. 
The Sucker-Fishes, —Family Gobioesogieje. 
The small fish (Lepccdogaster bimaculatus), of which three examples are 
shown in the annexed illustration, is one of three British representatives of a genus 
belonging to a small family which constitutes a sectional group by itself. Long- 
confounded with the lump-suckers, which they resemble in having an adhesive 
disc on the under surface of the body, the sucker-fish differ from that group, not 
only in the structure of that disc, but likewise in several other respects. They have 
no spinous dorsal fin; the soft dorsal and anal are short or of medium length, and 
situated far back, at the root of the tail; the pelvic fins are almost jugal in 
position, and have the adhesive disc placed between them; while the body is 
covered with a naked skin. Whereas in the lump-suckers the pelvic fins are close 
together, and actually form the base of the sucking disc, in the present family 
they are widely separated from each other, and only enter into the composition 
of a portion of the margin of the adhesive apparatus, which is completed by a 
cartilaginous expansion of the bones of the pectoral girdle. I 11 size the ovoid disc 
is relatively large, its length being sometimes as much as one-third that of the 
whole fish, and it is divided into an anterior and a posterior moiety, of which the 
second may or may not have a free front margin. All these fishes are littoral 
forms of small size, ranging over both temperate zones, where they are more 
TWO-SPOTTED SUCKER-FISH (liat. size). 
