THE NAUTILUS. 75 



" Upper tube marked with 8 and the lower with 4 faint longi- 

 tudinal lines or streaks, which terminate at the orifices in the same 

 relative number of short, thick and blunt cirri." 



Allusions are made to the anatomy of the animal of Thracia 

 conradi in comparing it with European species, but no figure of the 

 expanded creature has ever been published. The nearest approach 

 to a description of its habits is found in a monograph on the family 

 Osteodesmacea, by Joseph P. Couthony, 8 published seventy-five years 

 ago. In this monograph is first defined T. conradi as a distinct spe- 

 cies. He says : " The specimen of Thracia serving for the preceding 

 description was obtained in the early part of March last with the 

 living animal. It was buried about six inches below the surface at 

 low-water mark. An accident deprived me of an opportunity to 

 examine the animal, and repeated visits in search of another have 

 been wholly unsuccessful." Professor Verrill says : " The species 

 burrows so deep in the mud or sand that it is seldom taken alive with 

 the dredge." 



The specimen of Thracia conradi which I examined remained in 

 a vessel of fresh sea water for three days without a sign of life. At 

 one time the occupants of the house were away and there was no 

 vibration caused by their moving about, and then for the first time 

 the creature timidly thrust out its tubes. It was extremely sensitive 

 to any jar, and placing the pencil ever so carefully on the table 

 caused it to immediately retract. The tubes were entirely separate 

 and nearly as long as the shell. The excurrent tube was bent in a 

 sharp curve dorsally and the incurrent tube in a similar manner 

 ventrally. This attitude never varied, and it occurred to me that 

 buried in the sand it might rest its tubes on the surface as figured by 

 Meyer and Mb'bius of Scrobicularia piperata. Clark in the above- 

 mentioned work describes a similar attitude of the tubes in Thracia 

 phaseolina as follows: * * * " and posteriorly, for the issue of two 

 moderately long siphons, which are separate nearly their length, but 

 the animal always carries them in a divergent posture at the ex- 

 tremities * * * the tubes are capable of great inflation." The 

 tubes when fully expanded are white and translucent, the upper tube 

 having its orifice surrounded by six short blunt tubercles, while the 

 lower tube has its orifice surrounded by four similar tubercles. 

 These terminate in faint longitudinal lines, marking the siphonal 

 tubes precisely as described in the English species. At intervals the 



