76 Arenicolidae 



Clymenides sulphureaoi the family Maldanidae, 1 was a post-larval 

 example of Arenicola marina. The specimen, which was 3-4 mm. 

 long, was found in mud, surrounded by a mucous tube. There are 

 only two points in which Claparede's account does not fully apply to 

 a post-larval Arenicola marina, namely, his specimen is said to have 

 had twenty-two chaetiferous segments, whereas only nineteen are 

 present in A. marina, and oesophageal glands are neither mentioned 

 in the description nor shown in the figure (op. cit., Fig. 24) in which 

 the rest of the alimentary canal is represented. Nevertheless the 

 account is so fully in agreement with the characters presented by a 

 young Arenicola marina that we may conclude, with Prof. Mesnil, 

 that Claparede was dealing with a post-larval specimen of this species. 



Prof. Ehlers 2 described in 1892 the chief features of a young 

 Arenicola marina, 3 5 mm. long, enveloped in a gelatinous sheath, 

 taken in the plankton off Heligoland, and of a similar example, 

 taken at the mouth of the Ems, which was examined in sections, 

 and in which the presence of statocysts was ascertained. 



A more detailed account of " post-larval " examples of A. marina 

 was given by Prof. Benham 3 in 1893. This was based on two 

 specimens, collected near Plymouth, each about 6 8 mm. long, and 

 enveloped in a colourless, transparent sheath. 



Prof. Mesnil 4 states that Clymenides sulfur eus Clap, was taken 

 commonly in the townets at Wimereux in June and July, 1892 and 

 1893, and that the specimens were evidently similar to those studied 

 by Prof. Benham, and could be described, systematically and 

 anatomically, as young Arenicola marina, without gills and with 

 the crotchets of a Clymenid. Although these young worms so 

 closely resembled A. marina, Prof. Mesnil preferred to regard them 

 as Clymenides sulfureus, and as belonging to the family Clymenidae, 

 a conclusion to which he was impelled largely by the characters of 

 the crotchets. 



In his later paper (1897) Prof. Mesnil described two new species 

 of Clymenides, namely, ecaudatus and incertus. Though at first 

 inclined to regard the latter as the young phase of Brancliiomaldanc 



1 Quatrefages (Hist. nat. Annel., ii (1865), p. 249) placed Clymenides 

 sulfureus in the family Clymeniens (= Maldamdae) ; it was included in the 

 Maldanidae also by Prof. Racovitza (Arch. Zool. Exper., ser. 3, iv (1896), p. 229 

 and f.n.). 



2 Nachr. K. Ges. Wiss. Gottingen (1892), pp. 415, 416. 



3 J. Mar. Biol. Assoc., iii (1893), p. 48, pi. i. 



4 C. E. Soc. Biol. Paris, ser. 10, iii (1896), p. 388; Bull. Sci. France Belg., 

 xxx (1897), p. 144. 



