AN UNDESCRIBED ACRANIATE: ASYMMETRON 

 LUCAYANUM. By E. A. ANDREWS. With Plates XIII 

 and XIV. 



While the Johns Hopkins Marine Station was located at Alice 

 Town, North Bernini, Bahamas, in June and July, 1892, a small 

 amphioxus or lancelet came under observation and was at once 

 recognized as quite different from those commonly known. 



Owing to the very great morphological interest attached to our 

 knowledge of. the acraniate vertebrates, this new member of the 

 group has been studied and compared with the known lancelets 

 to determine to what extent it adds to the present conception of 

 acraniate anatomy. The result, as presented in the present article, 

 is that this Bahama lancelet is generically distinct, though morpho- 

 logically but little removed from the others in the main features 

 that make the acraniates isolated from all higher forms. 



Before stating what are these generic characters the habits and 

 habitat of the living animal, as far as known, may serve as a hint 

 of the possible explanation of some of those anatomical peculiarities. 



Examination of the very strong current that passes out from the 

 lagoon to the Gulf-stream between North and South Bernini fre- 

 quently resulted in the capture of large numbers of these small 

 lancelets. They were taken in the tow-net while swimming at or 

 near the surface; most abundantly at the early part of the ebb-tide 

 when it had been high tide about nine o'clock in the evening; 

 rarely in the daytime or late at night or on the rising tide. They 

 were also obtained buried in the sand-flats that furnish the charac- 

 teristic fauna of this ebb-tide current, but only a few could be found 

 here and there at the western end of Stokes Cay and also half a 

 mile to the east of East Point, East Wells. They may, however, 

 be much more abundant in these flats than would appear from the 

 above statement, since their small size and the soft permeable 

 nature of the purely calcareous sand would make their detection 

 much more difficult than it would be for such large lancelets as 

 Branchiostoma caribceum which we had taken in great numbers in 

 the firm continental sands of Tampa Bay, Florida. 



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