290 J. H. ASHWORTH. 



The prostomium of Scalibregma inf latum may be 

 described as almost T- shaped, the two horizontal limbs of 

 the letter representing the tentacular processes. The head 

 of Eumenia crassa is more deeply divided in the middle 

 line, and its lateral angles are rounded, and not prolonged 

 into tentacular processes (fig. lo). 



These two Polych^tes agree in the position and relations of 

 the nuchal grooves and peristoniiura ; in the appearance and 

 structure of the skin ; in possessing two kinds of setie, capil- 

 lary and furcate, in each of the rami of the parapodia; in the 

 presence of a sense organ between the rami of each para- 

 podium. 



Internally there is also a strong resemblance between these 

 two worms. (My specimens of Eumenia crassa were 

 unfortunately not in good condition internally, and I was 

 unable to determine some of the finer structural details.) 

 They agree in the following respects : — the general form and 

 relations of the alimentary canal, the situation of the four 

 anterior diaphragms, the musculature, the nou-ganglionated 

 nerve-cord, the nephridia, each with simple funnel leading 

 into a slender tube bent once upon itself, a considerable part 

 of the proximal limb of the loop being wider than the distal 

 limb. 



Scalibregma inflatum and Eumenia crassa differ 

 only (so far as their anatomy is at present known) in the 



body-wail (see fig. 18 b), and bear large flattened leaf-like dorsal and ventral 

 cirri. All other authors agree that the parapodia of E. crassa are without 

 cirri. In tlie Firth of Forth specimen there are six pairs of gills slated to 

 occur in front of the notopodium of the flrst six cha;tigerous somites. In 

 other recorded specimens of tliis Polyclisete the gills are situated behind the 

 corresponding notopodia. The prostomium of the Forth specimen terminates 

 in two diverging tentacles, thus differing from others (see above, p. 290). 

 These points taken in conjunction with the fact that the specimen described 

 by Cunningham and liamuge is an elongate worm gradually tapering 

 from about the eighth or tentii segment to the posterior end, whereas all 

 other recorded specimens are maggot-like, shows that this specimen, if it be 

 E. crassa, is quite different from any other example of this animal recorded 

 from the time of Oersted (1844) up to the present. 



