104 Bulletin Vanderbilt Marine Museum, Vol. VII 



Dr. Lo Bianco (1899) described this species as being one of 

 rare occurrence in Naples. 



The second record of the species from the Bermudas was given 

 by Dr. A. E. Verrill, of Yale University, in 1899, and in 1907, 

 this author published photographs of his specimens from these 

 Islands. 



Professors F. W. Gamble and J. H. Ashworth, of the faculty 

 of Owens College, Manchester, England, published (1900) a 

 memoir on "The Anatomy and Classification of the Arenicolidae, 

 with some observations on their Postlarval Stages," which con- 

 tains an exhaustive account of Arenicola cristata, excellently 

 illustrated. 



Diagnostic characters: This species attains a length of 

 twelve to sixteen inches and a diameter of one inch. The prosto- 

 mium is well developed, consisting of a median and two lateral 

 lobes ; the branchia occur in eleven richly pinnate pairs on somites 

 seven to seventeen, inclusive, and the nephridia in six pairs on 

 somites five to ten inclusive ; the posterior somites and pygidium 

 are characterized by the absence of branchia and parapodia; 

 these somites frequently but not always have small cirriform 

 processes. The anterior portion of the body is usually more 

 enlarged than the posterior. Arenicola cristata is one of the five 

 valid members of the genus and is readily distinguished by 

 possession of the most profusely pinnate branches found in this 

 genus. 



The brain is well developed, having anterior, median and pos- 

 terior lobes. The otocysts are closed spherical sacs, each contain- 

 ing a single, large, spherical chitinoid otolith, which is believed to 

 be formed by the secretions of the walls of the vesicle and appar- 

 ently increases in size throughout life. 



The nephridia are in six pairs, opening on somites five to ten. 

 These nephridia have the dorsal lip well supplied with flattened, 

 spatulate ciliated vascular processes ; the ventral lip is entire, cili- 

 ated. The oesophageal pouches are represented by only one pair, 

 which is variously cylindrical, clavate, or conical in shape. The 

 diaphragmatic pouches are large, finger-shaped. The gonad is 

 small. The ova are spherical, with a moderately thick vitelline 

 membrane. The segmentation of the ova is complete, but some- 

 what unequal. 



