108 A rejiicolidae 



Stimpson's type is apparently no longer in existence/ but Liitkeu's 

 specimens are preserved in the Universitetets Zoologiske Museum, 

 Copenhagen, and were recently examined by the writer, who found 

 them to agree in every respect with examples from Florida, Carolina 

 and Massachusetts. 



Profs. Mesnil and Fauvel included in this species A. glacialis, 

 which, at the time of publication of their memoirs, was insufhciently 

 described, but the writer has shown that A. criMata and glacialis are 

 distinct species. 



Bionomics. — Like other species of Arenicola, A. cristata seems to 

 be more abundant in sand containing a considerable proportion of 

 decomposing organic matter (Lo Bianco, 1899 ; Lillie, 1905). 

 Mr. Cyril Crossland found specimens near Suez in clean sand, but 

 this was rich in Foraminifera, which no doubt served as food for the 

 worms. 



A. cristata descends in the sand or mud to a depth of twelve to 

 eighteen inches, or, in some cases, two feet. The burrow, in which 

 the worm is found head downwards, is, according to Stimpson, at 

 first vertical and then almost horizontal, and thus resembles that 

 usually made by a Laminarian example of A. marina. The entrances 

 to the burrows of the massive American specimens of A. cristata are 

 large and conspicuous. 



Mr. Crossland has informed the writer that the burroM's of 

 A. cristata, which he saw at Suez, were very deep and (J -shaped, 

 and, like those of littoral examples of A. marina, their two ends 

 were marked respectively by a heap of castings and a funnel-shaped 

 depression. 



Size. — This is the largest species of the genus. Stimpson saw 

 one or more specimens sixteen inches (400 mm.) long and an inch 

 in diameter. The writer has had six specimens from Wood's Holl, 

 each exceeding 400 mm. in length ; one of them was a veritable giant 

 among Polychaeta, as it had attained a length of 515 mm. (the 

 tail was 190 mm. long) and a girth of 75 mm. Specimens almost 

 as large have been received from Florida and North Carolina. Most 

 American examples, though large, are, however, considerably shorter 



' The Curator of the Boston Society of Natural History, to whom I wrote 

 for information regarding the type specimen, kindly informs me that it is not 

 in the Society's Museum, but that it was probably in Stimpson's own col- 

 lection, and, if so, was in all likelihood destroyed with the Chicago Academy 

 of Sciences in the great Chicago fire. 



