254 MR. C, F. ROUSSELET ON THE POLYZOA [Mar. 5, 



Fredericella cunningtoni, sp. n. (Plate XV. figs. 9 & 10.) 



Specific Characters. — Zoarium consisting of creeping, closely 

 adherent, branching and intei'lacing ^-shaped tubes, built of a 

 very thin, transparent, chitinous, internal membrane, covered 

 externally with coarse grains of sand ; lophophore circular, with 

 16 tentacles. 



The appearance of the tubes of this new species is such that they 

 were at first passed over as apparently the tubes of some aquatic 

 worm or insect larva, until a circular lophophore was observed 

 protruding from one of the tubes, when a closer examination, 

 and the removal of the adhering tubes, revealed an abnormal 

 Polyzoon, 



Though the indifierent preservation of the specimens did not 

 allow me to ascertain with certainty whether an epistome is 

 present or not, all the other characters are those of a phylacto- 

 Isematous Polyzoon ; and as the lophophore is cii*cular, the genus 

 Fredericella naturally suggested itself. 



The tube is low and ^-shaped in section, very closely adherent 

 to the surface of shells and stones, branching and intei'lacing 

 freely. The structure of the tube is very abnormal ; it consists 

 of a very thin, transparent, chitinous layer, to the external 

 surface of which grains of sand of vaiious sizes and colour are 

 cemented, not unlike the tubes of some marine worms. The 

 grains of sand are mostly angular white quartz, and, to a less 

 extent, green olivine, interspei'sed with red and black grains, and 

 occasionally some plant and shell fragments. A few specimens 

 show tubes made of finer sand-grains. Only the raised ends of 

 tubes are tubular, otherwise the whole of the creeping tube is 

 ^-shaped, the adhering surface being free from grains of sand. 

 The cells of the polypides are long, continuous, and with a few 

 incomplete septa here and there. The width of the tubes is 

 346 /i (y-j- in.) on an average. 



The lophophore is circular and has 16 tentacles, but the rest 

 of the anatomy could not be made out, owing to the bad state of 

 preservation. No statoblasts were found in the tiibes. 



Hah. Encrusting stones and Neothauma shells dredged in 

 about 10 fathoms at Kibanga, and also shells dredged in about 

 25 fathoms near Mshale. 



The genus Fredericella has contained, so far, only one species, 

 i. e. F. sultana of world-wide distribution, if we consider the 

 three American forms F. regina, walkottii, and pidcherrima 

 as synonyms of F. sultana, in accordance with the opinion of all 

 recent authorities. F. duplessisi, found by Dr. F. A. Forel 

 (2, 3, 4) living unattached in the soft mud at the bottom of the 

 Lake of Geneva, also is but a F. sidtana which has adapted itself 

 to its environment. Having examined specimens dredged by 

 Dr. Forel, consisting of short tubes with few bi^anches, not 

 exceeding half an inch in length, I can find no difference between 

 them and the type species. I should like to mention here that I 

 find the tubes of F. sidtana rarely cylindrical, as has usually been 



