316 NEREIS DIVERSICOLOR. 



prominent as a single process. The ventral lobe is minute, and the ventral cirrus is a 

 small filiform organ behind the ventral edge of the foot. 



Habits.— As the early authors observed, this Nereid burrows in the clayey mud often 

 in estuaries where the water must sometimes be brackish. Moreover, the entrance of 

 sewage into the water does not seem harmful to it, and the dark mud is often odori- 

 ferous, yet there it lives and breeds. Horst l gives some interesting notes and references 

 on this subject, quoting especially the experiments of Ferroniere and Metzger. 



Mr. Goodrich 2 gives an account of a "new dorsal organ in every segment," except a 

 few after the first and before the last; and consisting of a pair of large ciliated patches 

 of coelomic epithelium present in most species of the Nereids. He considers it a genital 

 duct not fully developed. He also notes that the nephridium consists of a compact mass 

 perforated by a convoluted canal. The nephrostome has long ciliated processes com- 

 municating with the anterior by a short duct on the ventral surface (nephridiopore). 



Reproduction. — Various statements have been made about the reproduction of this 

 species. Thus Max Schultze 3 refers to the occurrence of the young in the body-cavity, 

 having apparently considered Koch's statements in regard to Marphysa sanguined as 

 correct. He describes them as pea-shaped, reddish-yellow embryos, with mouth, rudi- 

 mentary digestive system, two eyes, and small pits or furrows (" Lochern ") under the 

 feet. 



Cuvier and Grube, again, thought Arenicola was hermaphrodite, and Ratlike placed 

 Amphitrite in the same category, though each might be more or less male or female. An 

 interesting resume of the views of the period is given by Frey and Leuckart. 4 Claparede 

 and Mecznikow 5 give an account of Cirraiulus chrysoderma, Clpde., an adult of which 

 presented at each side in the median region of the body ovoid sacs, which were at first 

 thought to be parasitic Crustacea. They proved, however, to be young Cirratulids, one 

 figured by the authors showing an elongated body, two eyes, two pairs of filiform 

 branchiae, with several bristles and hook-bearing segments behind, and a fairly complete 

 alimentary apparatus. A. Krohn, 6 again, describes from Nice a viviparous Sijllis 

 (S. vivipara) allied to S. Armandi, only the new form has simple tips to the terminal 

 pieces of the bristles. The enclosed young form has twenty-three segments, and is like 

 the adult. 



In F. M. Balfour's 'Embryology' 7 it is stated that "a few forms (e.g., Eunice 

 sanguinea, Si/llis vivipara, and Nereis diversicolor) are viviparous." Considerable reliance 

 in more recent times has been placed on the observations of Mendthal on the supposed 

 hermaphroditism of Nereis diversicolor. This author seems to have been attracted to the 

 subject by the previous work of Schroder, 8 but beyond the general and incorrect view 



i l Tijdschr. d. Nederl. Dierk. Yereen ' (2), Dl. xi, p. 142. 



3 ' Quart. Journ. Micr. Sci.,' April, 1893. 



8 ' Entwickehmg Arenicola piscatorum, etc./ p. 214 (Halle, 1856). 



4 ' Beitr. z. Kenntniss wirb. Thiere/ p. 82 (1847). 



5 < Zeitschr. f. wiss. Zool./ Bd. xix, p. 192, sep. abdr., p. 30, Taf. xiv, f. 4. 



6 l Arch. f. Naturges./ Bd. xxxv, p. 197, 1869. 



7 Vol. i, p. 319. 



8 ' Anat.-histol. Untersuch. von Nereis diversicolor ,' 0. F. M., Rathenow, 1886, p. 35. 



