1899] EPITOKOUS FORMS OF ANNELIDS 377 



South Pacific affords features closely resembling the epitokous or 

 epigamous condition. Regularly, in October and November the sea 

 around the coral reefs of the islands swarms with fragments of the 

 posterior region of these annelids laden with ova or spermatozoa, but 

 without much change in the bristles. So abundant are they that for 

 centuries the natives have collected them for food. 



The Onuphidae, Goniadae, Glyceridae, Opheliidae, Scalibregmidae,. 

 and Telethusidae offer, so far as known, no examples of epigamy. In 

 the Chloraemidae the authors hint that Bvshiella ahyssorum, MTntosh, a 

 form apparently intermediate between the Chloraemidae and the Chaetop- 

 teridae, and stretching over a wide area at great depths in the ocean, is 

 an epitokous form, an opinion that is hardly warranted by the facts. 



The epitokous condition has not been observed in the Chaetopteridae, 

 or in the Spionidae, though the latter in their young stages are amongst 

 the most conspicuous features of the pelagic fauna. It is likewise 

 absent from the Ariciidae. 



In the Cirratulidae the epitokous condition is present in Dodecaceria, 

 and it may be in others, such as Chactozonc, while schizogenesis occurs 

 in Ctenodrilus? In the Halelminthidae, Eisig has shown the detach- 

 ment of the posterior region with the generative products, but without 

 change of the bristles. Nothing of the kind is known in the Maldanidae, 

 Ammocharidae, Hermellidae, Amphictenidae, Ampharetidae,Terebellidae, 

 Sabellidae or Eriographididae, but in the Serpulidae we have schizogenesis. 



The epitokous condition thus characterises Polychaets of consider- 

 able activity, the only instance in which it is present in a boring or in 

 a fixed tube-making form being in the Cirratulidae, for the Nereids and 

 Eunicids, though they construct tubes, are comparatively active. 



The form which the authors have added to the list of the epitokous 

 annelids was originally described by Oersted, and is not uncommon in 

 the northern seas, though our experience of it in Britain is that it is 

 more abundant in the south. 



The authors find three well-marked phases in the life-history of 

 Dodecaceria, viz. (1) the sedentary atokous, or ordinary form (A) ; (2) 

 the large epitokous sedentary form (C) ; and (3) the epitokous pelagic 

 stage (B). 



The first-mentioned form (A) is dark greenish-brown, slightly 

 tapered anteriorly and more distinctly posteriorly. The first region 

 includes the prostomium, and the following segments to the 5th or 

 7th. The prostomium is devoid of appendages, and presents only 

 a pair of ciliated pits. The next segment (the first metastomial of 

 the authors) bears the grooved palps and two branchial cirri. The 

 succeeding segments (generally 5) have capillary bristles, some of those 

 iu the ventral division having a tendency to be spoou-shaped. The 

 authors term this region the thoracic, and it bears the branchiae to the 

 number of 5 or 6 pairs. The rest of the body is nearly uniform in 



1 The position of this form is that assigned to it by the French authors. 



