Garman.] 170 [November 4, 



It is a most dissatisfying use of a man's writings thus to make Mm 

 a believer in what he never did believe, and never knew that any- 

 one was ignorant or audacious enough to have suggested. 



On the Skates (Ra«le) of the Eastern Coast of the 

 United States. By S. W. Garman. 



All of the sharks, skates, and rays possess the spiracle at some 

 period of their existence, but in the adults of some it is difficult to 

 discover, if not quite obsolete. This is an opening through which 

 the water may pass from the upper surface of the head into the 

 mouth cavity. It is placed between the eye and the cartilage (hyo- 

 mandibular) joining the jaws to the scull. In front of it is a strong, 

 flat, crescent-shaped cartilage, attached at one end to the hyoman- 

 dibular, reaching out toward the skull, and having a strong muscle, 

 the contraction of which forces the inner end backward, at the same 

 time turning the upper edge in such manner as to close the opening. 

 Only among those species whose habits confine them closely to the 

 bottom is the spiracle found in its perfection. The sting rays (Try- 

 gon, Pteroplatea, Rhinoptera, Myliobatis) have, proceeding from the 

 upper edge of the cartilage, a valvular fold, which is turned inward 

 so as to open for an inward, and be closed for an outward, current. 

 These are broad, flat-bodied creatures, with all their protective armor 

 or weapons on the dorsal surface, with eyes so situated as to allow 

 them little or no chance to see downward, and with teeth flat and 

 pavement-like, for crushing the Crustacea, molluscs, etc., on which 

 they feed. Unfitted by their structure for darting through the water 

 at all depths and gaining a living as do the round-bodied sharks, 

 they spend their lives creeping over the sand and mud, finding with 

 their noses such prey as is hardly able to make an effort to escape. 



The majority of the sharks allow the water to pass freely through 

 the mouth and out of the gill-openings; they, however, live in mid- 

 water, and can do so without experiencing the least inconven- 

 ience ; but were these bottom feeders to do the same, keeping the 

 sediment stirred up as they do in their search for food, they would 

 continually bring coarse, harsh, gritty material in contact with the 

 delicate branchial membranes. Instead of this, on any enlargement 

 of the mouth cavity, the purer water is taken from above the body 

 through the spiracle to pass out through the branchial aperture. A 

 valve-like fold which hangs across the mouth from the base of the 



