I 20 



while the specimens from the Azores are said to belong to two species, R. gri)naldii Jullien, 

 and R. inaiiubialis Jullien. 



R. noriiiaiii appears to be characterised by the great length of the peristomes, or free 

 cylindrical parts of the tube. R. conipacta is said to have very short, crowded peristomes. 

 R. grinialdii has a short peristome, continuing a creeping portion of equal length, which is 

 characterised by the presence of "deux tubes tres fins, convergeant par leur extrémité antérieure", 

 and running longitudinally along its free wall ; while the orifice is somewhat expanded. In 

 R. luamtbialis the peristome is about twice as long as the attached portion of the zooecium, and 

 lts tube-rings .seem to be very prominent. The species is not, however, very well characterised, 

 although it is said to differ from R. griinaldii by the colour of the coenoecium (yellowish instead 

 of brovvn), by the absence of the two "tubes" of that species, and by the fact that the axial cord or 

 pectocaulus extends into the attached part of the zooecium, which is not t.\\& ca.?,e. 'm R. gr'inmldii. 

 The specimen dredged by the "Siboga" is a perfectly typical Rhabdopleura, its coenoe- 

 cium consisting of a creeping portion attached to 

 the stone, and provided with the characteristic, dark 

 brown pectocaulus embedded in its lower wall. 



I have been able to examine only two 

 peristomes which appear to be complete. The 

 specimen figured (^) consists of 1 3 rings, the last 

 of which seems to have been somewhat distorted 

 during the preparation of the slide. The rings are 

 much more prominent than in R. uoi-iiiani, giving 

 the peristome an annulated appearance. As in that 

 species the substance of the ring is not completely 

 continuous, but is interrupted by a suture (.^-.j, which 

 Is visible, however, only in cases in which It happens 

 to occupy a favourable position. In the creeping 

 portion of the zooecium (/y), the sutures have the 



2. — J\/ialHi'oplciira ^n.iSiM. 20A). ^, a complete peristome, i , • .• • i- . . i • 1 i i_ 



. . . ^ ' ^ r , ■ \.^. characteristic zigzag disposition which has been 



onginating from part of the creeping portion of the coe- r 



noecium: /.'. fragment of the creeping portion: (7., üiificc; notlcecl in Otlier SpecIeS of Rkabdoplcitra . The 



/., pectocaulus; j., suture of tube-ring; ■>£'/•, septum; .f., . . . ,, . , . . ^ 



mass of detritus (x 80: magnified to the same extent as JUUCtlOUS ol SUCCesSlve lamellae lU thlS portlOn fomi 



the free end of the peristome of /,'. nvr,„a„i sheun in ridges whlch, however, arc uot so prominent as 



PI. II, fig. 19). . ' 



those of the peristomes. The creeping part is inter- 

 rupted by transverse septa {A, sep.), as in other species of the genus, and its lower or attached 

 wall contains the tubular pectocaulus (/.). The preparation shews one zooid, with recognisable 

 tentacles, and indications of several buds '). 



Fig 



l) The stone on which the Rlialidoplciira was found Ijore several tubes which in size and iii being composed of a series of 

 dislinct rings have a curious resemblance to the peristomes of Khalnioplciira. One or two of these structures were in fact mounted under 

 the impression that they belonged to that genus. Their wall is, however, much thinner than in R^habdopletira^ the rings are made up 

 of a series of smaller segments, and the tubes are conical instead of being cylindrical in form. There can be no question that they belong 

 to Stcphaiioscyplius^ and I am unable to distinguish them from 5. iiüyabiHs described by Allman in 1875 (Trans. Linn. Soc, (2), Zool., 

 I, p. 61). Professor Cll. Julin, to whoni I sent a preparation of the organism, informs me that he agrees wiih this determination. 



