PALLASIA MURATA, N. SP. : A NEW BRITISH SABELLARIAN. 301 



the hinder portion of the ' hood - shaped structure,' is bordered by 

 a curved row of ten rounded, cushion-like lobes, and laterally there 

 is on each side a much larger conical lobe, as in Sahellaria* Outside 

 this conical lobe lies the neuropodial cirrus of the first segment, and 

 externally to this again a small rounded lobe, from in front of which 

 the short neuropodial bristles of this segment arise. 



The two tentacles are best seen from the ventral surface of the 

 worm. They arise behind (dorsal to) the lip, and extend a little 

 beyond the anterior ends of the peristomial lobes. The tentacles 



* After tlie above was written I sent the specimen of Pallasia to Mr. Arnold Watson, 

 who is at present engaged in a study of the British Sabellarida?. Mr. Watson lias kindly 

 allowed me to print here tlie following valuable note exjilaining his views as to the nature 

 of the structures which surround the mouth : — 



"The hood-shaped structure which surrounds the mouth (well shown in Figs. 1 and 3) 

 is really formed by the ui)per and lower lips combined ; the lop jwrtion lieing due to the 

 former, and tiie side folds to the latter. As the result of recent study of the British 

 Sabellaridffi {S. alveolnta and S. spinulosa) I have found that the lower lips (by means of a 

 membranous structure winding in and out between the tentacular fans) are practically 

 extended to the distal extremities of the peristomial lobes, while the upper lip is similarly 

 but more directly so extended right and left, a few foldings only (less than a dozen on 

 either side) occurring anteriorly, and each fold corresponding with the position of a single 

 tentacular filament placed in the inner margin of the peristomial lobe. The membranes 

 which proceed from the upper and lower lips respectively coalesce at the extremity of the 

 lobes. The result is the formation of a ciliated channel running the length of each lobe, 

 receiving, by means of the transverse folils, the material collected by the fans and by the 

 intcrn.-il filaments, and conveying it to tlie mouth of the worm, there to be used for food or 

 for building purposes. An arrangement, similar in principle, but differing in detail, appears 

 to exist in Pallasia. 



"The hood-shaped structure, the product of the upper and lower lips combined, is com- 

 moa to all. Fear of causing injury by manipulation of the tentacular filaments, etc., to the 

 specimen Pallasia, has prevented my making a satisfactory examination, Init by careful pos- 

 ing and illumination it can be seen that the margin of the npjier lij), though shallower, runs 

 forward (and not backwards, as would be needful to form a liood), and that it is intimately 

 connected with the first of a series of filaments which border completely the inner edge of 

 the peristomial lobe. For the reason before given, the course of the lower li]is cannot be 

 followed, liut from appearances and analogy with Sahellaria, each lip is probably connected 

 with the inner edge of the first external fan. An avenue or channel is thus formed 

 between the inner and outer sets of filaments, leading to and carrying material to the 

 mouth in the way already explained. 



"The main difference to be noted is, that whereas in Sahellaria there are only few inner 

 tentacular filaments, and those at varying intervals, in Pallasia the inner margin of the 

 lobes is by their means completely and compactly fenced. Viewed from the dorsal surface, 

 these inner filaments seem to have a fan-like arrangement somewhat similar to those in the 

 outer edge, but not quite so well defined. 



"The 'curved row of cushion-like lobes,' combined with the 'larger conical lobes,' 

 forms the ' building organ ' of the worm. They are glandular structures, and doubtless 

 supply tiie cement with which the sand, stones, and sliells are attached. I have seen the 

 whole in action in Sahellaria, and by means of sections the glandular structure of the organ 

 has been jiroved. Tiie peculiar columnar arrangement of the glands is, in Pallasia, to some 

 extent indicated by its external appearance. In Sahellaria the glandular portion, although 

 crenate on its edge, is not distinctly divided into cushion-like lobes. Probably the latter 

 arrangement in Pallasia is a modification enabling the worm to deal more easily with the 

 very bulky material used in the construction of its tulie, Aknoi.h T. Watson." 



