2. MYXINID^ BDELLOSTOMA. 5 



tail representing tlie .si)iiial column. ^Moulli round, suctorial, witliout 

 lips, "with a pair of barbels on each side. ^Nostril single, large, on 

 the median line above, and at the very front of the head, provided 

 with two i)airs of barbels. Teeth strong, a single median one on the 

 roof of the mouth, and two rows on each side of the tongue, v.iiich is a 

 powerful organ, with a strong fibrous tendon moving in a nmscular 

 sheath. Alimentary canal a simple, nearly straight tube. Gill-sacs 

 placed on each side of the oesophagus, lying directly against its outer 

 Avails. The water passes iuto them by a small pore opening directly 

 from the oesophagus into each sac. It is then i)assed out by a duct, 

 which continues backward along the outer walls of the sacs to the 

 abdominal wall at the end of the last sac, where all the ducts from one 

 side unite in one, and the water is emptied at the branchial opening on 

 each side of the median line. In close connection with the branchial 

 opening on the left side there is a third opening that leads by a very 

 short duct to the o'sophagus, and hence into the branchial sacs, at 

 times when the supply through the mouth is cut oft' by the head being 

 buried in the food of the animal. Ovary single, on the right side. No 

 oviducts ; the mature eggs falling iuto the abdominal cavity are excluded 

 through the j)eritoneal opening at the side of the vent. — {Putnam.) 



A single species; colorless, parasitic animals, burrowing into the 

 bodies of fishes, and found in all temperate seas. (,a'3|«, slime.) 



2. ]TI. g'Sutitlosa. L. — Hag-fiHh; Borer; Sleepmarlen. 



Blue above, whitish below; head 3.^ to 4 in total length ; tail CJ to 10 



times in total length; lingual teeth 8 to 11 in each row (Putnam). 



Coasts of Europe and America; not abundant on our shores. 



(L. Syst. Natma; ; Giiutlier, viii, 510 ; Putnaiii, Proe. Bost. Soc. Nat. Hist. 1873, 135 : 

 Myxine limona Guard, Proc. Ac. Nat. Sci. I'liila. 1858, 223.) 



3.— BDELLOSTOMA Miillcr, 1834. 

 (Miiller, Ahliandl. Akad. Wiss. Wieu, 1834, 79 : tj'i)e Petromiizon cirrhatits Forster.) 



This genus differs from Myxine chiefly in the structure of the bran- 

 chial apparatus, there being six or more sacs on each side which receive 

 water directly from the u'sophagus as in Myxine^ but the emptying 

 ducts, instead of passing backward and downward to a common exter- 

 nal opening, as in Myxine., pass directly through the wall of tlie body, 

 so that there are as jnany external openings as there are gill-sacs. Warm 

 seas. (;3''iAA«r, leech; <77r;//.«, mouth.) 



