neto '^^Wurm^' from Lower Ludlow Beds. 131 



It is, Iiowever, to be noted that, whereas the Orilovician 

 and Silurian species of Protosculex are <is.-»uciated with marine 

 organisms in deposits ot" admittedly marine ori<;in, I*roto- 

 scolex curio/Jcir/i/s is associated with various arachnids, insects, 

 and a millepede, in a deposit of presumably fresh- water, or 

 possibly brackish-water, origin. 



Beddard (1895, Monogr. Oligoehfeta, p. 9) says of Pro- 

 naidiles that " it is not by any means convincingly an 

 Uligochaet." At the same time he brings forward no counter- 

 arguments, except in so far as he seems to suggest that, if it 

 weie, then it would sup|)ort tiie view that Oiigochfeta were 

 derived from the Polyelueta by way of such tonus as the 

 Tubificidse — a view with whicli he disagrees. Boddard's 

 argument in the paragraph quoted depends on the distribution 

 of the setpe, but he can have known nothing about the setai 

 of J-*, curboiiarius, and must therefore have connected it with 

 the Tubificidaj simply on account of its habitat. If, how- 

 ever, the papillae of other species of Protoscolex justify the 

 conclusion that the setae were arranged as in Porichretidae, 

 then the question assumes a totally ditfereiit aspect. 



Beddard's own view is that the perichoetous arrangement 

 of setae is the primitive one, and for this view Protoscolex does 

 seem to furnish that paljeontological evidence the absence of 

 which he deplored. So far as the known structure o'i Proto- 

 scolex permits of a decision, there is no reason why the genus 

 should not be referred to the Perichaetidse. It might, how- 

 ever, be too hazardous an inference to suppose that this family 

 of recent earthworms had true representatives in the Ordo- 

 vician sea, and it is more probable that Protoscolex was 

 nearer to the hypothetical Archicha3tO[)od from which the 

 Phreoryctidae, Moniligastriche, Encliytr<eidte, and Perichae- 

 tidai originated. It is already a good way removed frum 

 anything that cuuld be called an Archannelid. 



Fortunately it has been possible to submit this instructive 

 specimen of Protoscolex latus to Dr. Beddard and to Professor 

 Seiiaro Goto of Tokyo, and each has independently expressed 

 ihe opinion that it closely resembles a modern perichtetid. 

 The preceding speculations have therefore the sanction of 

 good authority. At the same time they are speculations ; 

 other interpretations aie possible, and it n)ay be safest to 

 summarize only the certain facts in the following 



Revised Diagnosis vf Protoscolex. 



A worm-like marine organism, probably cylindrieal> 

 tapeiing rapidly at each end ; length from about 'lb mm. to 

 100 nun. ; width in the compressed fossil from ()■;') to iJ mm. 



9* 



