64 Journal of the Mitchelx, Society [^August 



largely by sting rays. Another 140° of its circumference is bounded 

 by a shallow gently sloping rock bottom on which the water a half mile 

 from shore will not be over a man's shoulders. On this rocky bottom, 

 the nurse sharks, Ginglymostoma cirratum, come out to bask in the sun, 

 to play, to breed, and possibly to feed. Here they are found in large 

 numbers. A dozen can be seen at almost any time, and 33 have been 

 counted in the sweep of the eye. 



These sharks in looks and habits much remind one of well fed pigs 

 in a barnyard. They are much broader in the pectoral region than 

 ordinary sharks, are sluggish in their movements, and are comparatively 

 unafraid of man. They frequently lie in water so shallow that their 

 dorsals project above the surface, and a number of times they allowed 

 the boat to drift down over them and strike their fins before they would 

 move. 



They lie with heads on each others pectorals or tails, or one will have 

 his snout elevated on another's flank, or they will lie heads and tails 

 together or in a confused herd. Here again this similarity in habits to 

 barnyard pigs is very noticeable. Further they often swim one after 

 another to the number of three or four in an aimless fashion, each one 

 following the purposeless turnings of its leader. 



They are perfectly harmless. Their mouths are small and filled with 

 small pointed teeth. They are omniverous in feeding, like most sharks, 

 but their food seems chiefly to be crustacean, probably consisting of 

 the large spiny "crawfish" common on the reef and on rocky bottom of 

 any kind. 



Under the circumstances noted above, there is, of course, no difficulty 

 in killing these sharks. Ordinarily shark fishing is good sport, but kill- 

 ing nurse sharks is no more exciting than sticking pigs in a barnyard. 

 Indeed the Key West fishermen contemptuously speak of them as 

 "Nurses", and of the other sharks as "sharks". 



Work on the habits and embryology of this shark is being carried on 

 under the auspices of the Marine Laboratory of the Carnegie Institution 

 of Washington situated at Tortugas and will be continued this summer. 



FLOWERS AND SEED DEVELOPMENT OF SPECULARIA 



PERFOLIATA. 



H. R. ToTTEN AND J. A. McKay. 



There are two kinds of flowers, conspicuous open ones with normal 

 corollas and small bud-like flowers that never open. The last or cleist- 

 ogamic flowers were described carefully by von Mohl, as long ago as 

 1863. 



It is the object of this paper to give the development of the seeds in 

 the cleistogamic flowers. The seeds are of the same size and appearance 

 as those borne in the open flowers. Four megaspores are formed and 



