118 PEOCEEDIXGS OF UNITED STATES NATIOXAL MUSEUM. 



" What we have termed the head is measured from the anterior 

 extremity of the buccal disk to the first brauchial orifice, the chest 

 being the region occupied by the entire series, seven in number, of the 

 same branchial orifices. 



" The length of the head is equal to that of the chest. The tentacles, 

 at the periphery of the buccal disk, are inserted into a shallow groove, 

 formed exteriorly by the thickened edge of the disk, and interiorly by 

 a soft and flexible membranous ridge. The friuges themselves are more 

 developed posteriorly than anteriorly. The branchial orifices are sub- 

 circular, provided with two semi-circular lips, au anterior aud a i^osterior 

 one, fringed upon their edge, and somewhat raised above the surface 

 of the chest. 



" The dorsal fin exhibits two convex elevations, one anterior to the 

 vent, the other posterior to it. Its continuity with the caudal is marked 

 by a gradual shallow depression. The lower lobe of tlie caudal is rather 

 more developed than the upper lobe. The tail itself is bluntly spear- 

 sbaped. 



'^•Tlie color is of a uniform chestnut tint, somewbat lighter along the 

 abdominal region than over the sides and back, which is much darker." 



The single typical specimen was catalogued at number 979. It was 

 collected by Dr. George Suckley at Galena, Minn. 



In the example received from Mr. Moore the following characters are 

 observed : 



Head 7f in total length; body and tail compressed. Labial fringes 

 short everywhere, but more developed posteriorly than anteriorly. 

 Maxillary teeth pointed, close-set, three in number; maudibulary plate 

 crescent-shaped, with nine pointed teeth very gradually diminishing in 

 size from the middle tooth to each end. Two of the lateral teeth on 

 each side of the oral aperture bicuspid, the rest uuicuspid. Both series 

 of lingual teeth finely pectinate. Eyes very small, obscure. Spiracle 

 iibout once its own length in front of eyes. Origin of dorsal fin midway 

 between spiracle aud end of tail. The dorsal fin is continuous, low in 

 the first half of its length (about one-sixth the height of the part of the 

 body under it), thence gradually rising to its greatest height a little 

 behind the vent and again gradually diminishing to the emargination 

 which separates it from the tail. The greatest height of the dorsal is 

 less than one-half that of the body at the same point. The distance of 

 the vent from end of tail equals 3 times height of body at vent. The 

 space occupied by the gill-openings is about equal to length of head. 

 Greatest height of body equals head to hind margin of eye. The tail 

 small, no part of the fin surrounding it being much higher than the 

 anterior half of dorsal. 



The alcoholic specimen now is almost uniforndy light brown replaced 

 by chestnut in one small area on the belly a little in front of vent. The 

 spots on head, chest, and back, which Mr. Moore descril^ed as blue, are 

 now dark brown or nearly black, resembling fly-specks. 



