No. 447-] H AMINE A SOLITARIA SAY 



217 



{Pseiidopleuronactes amcricanus) caught at \V(K)d's Holl in 

 August, contained a large number of the shells of Bulla solitaria." 

 The winter flounder is dredged in the vicinity of Wood's Holl at 

 a depth of about fifteen to thirty feet, and is mentioned by 

 Verrill as devouring Bulla in large numbers. Haminea has been 

 dredged in May in Hadley Harbor at a depth of twenty-five feet. 

 These facts would tend to show that its natural habitat for the 

 most of the year is the deeper water. A further proof that 

 H. solitaria lives in deep water except during the breeding sea- 

 son is supplied by the following facts : August 28, 1900, Dr. C. 

 V. Wilson while skimming the surface water with a fine mesh net 

 near Edgartown, secured a large number of H. solitaria. They 

 all died during the first night although they were placed in a 

 small aquarium. The time that these individuals were collected 

 was after the usual egg laying periods for the forms that live in 

 the vicinity of Wood's Holl. When taken, they were evidently 

 migrating into the deep water. The observations of Verrill 

 and those of Wilson seem to show conclusively that H. solitaria 

 is a deep sea dweller except for about six weeks, when it takes 

 up tempofary quarters in some favorable place in shallow water. 



During the first two summers that H. solitaria was under my 

 observation I was unable to discover any evidences of copulation, 

 owing to the fact that early in the season I did not have in the 

 laboratory any considerable number of animals ; but in the sum- 

 mer of 1900 1 had in the laboratory about forty animals at one 

 time and was able to make observations on copulation. The 

 habit which these molluscs have of crawling over one another 

 and of collecting into a pile, concealed the fact and method of 

 copulation for a long time. One day, however, I noticed two 

 animals apparently copulating, the genital grooves were slightly 

 extended and came together, from one the penis protruded into 

 the genital groove of the other. The animal receiving the penis 

 laid a mass of eggs eight hours after the copulation, the other 

 one did not lay. In a second case of copulation the animal laid 

 after the lapse of thirty-six hours, but this was an unusually long 

 time and probably due to the unnatural conditions surrounding 

 it. In the time that elapses between the period of coixilation 

 and deposition, H. solitaria is similar to many of the luidi- 

 branchs (Small wood :03). 



