174 



WILSON. 



[Vol. I. 



But two specimens were obtained September 4 and placed in 

 an aquarium. One of these, which proved to be a female, was 

 injured in the digging, and while being put into the aquarium 

 some nearly ripe eggs escaped through the rent in her side. 

 These furnished the necessary stimulus for the uninjured male 

 and he soon sent out ripe sperms in large • quantity from the 

 nephridia. 



This would indicate a breeding season for that locality of 

 September to November. 



In the female just mentioned the nephridia were perhaps 

 one-eighth full of eggs ; all the rest of the eggs were free in 

 the body cavity. This was the only specimen in which any 

 eggs were found in the nephridia, but they may sometimes be 

 found in the body cavity in June, and probably require a long 

 time for development. When ripe (i.e., those from the recep- 

 tacles) the eggs are spherical, about 0.3 mm. in diameter and 

 nearly opaque, but until fertilization the large germ nucleus 

 can be plainly seen through the yolk granules. 



The spermatozoa have a peculiar bullet-shaped head, a short 

 cylindrical middle piece, and a long, very delicate tail. Their 

 vibratory movements are rapid and very strong, and they retain 

 the power of motion for a long time after being discharged 

 into the water. 



Just enough description has been here given to fix the spe- 

 cies definitely, but considerable work has already been done on 

 the morphology and histology of the body organs and on the 

 origin of the sexual products, and it is expected that the near 

 future will afford an opportunity for a careful study of the 

 complete life history of this interesting species. 



Through the courtesy of Dr. W. R. Coe, of the Sheffield 

 Biological Laboratory at Yale University, I have received 

 specimens of an Echiurus secured by him in Alaska, while on 

 the Harriman Alaskan Expedition during the summer of 1899. 



This species was found abundantly at many different locali- 

 ties along the Alaskan coast south of the Peninsula and on 

 adjacent islands, nearly always in rich black mud. 



It is of considerable interest to note that it proves to be the 

 same species here described, viz., Echiurus Pallasii, and that 



