KUNOL. SV. VET. AKADEMIENS HANDLINGAR. BAND 47. N:() I. 25 



are replaced by the minute elevations on tlie truncated end of the body, which are 

 distinguishable only under a higher magnifying power. 



The nerve-cord is discernible as a light line along the ventral surface of the 

 trunk (fig. 13). 



The caudal appendage, representing a direct prolongation of the body and 

 its cavity, has a club-shaped appearance, narrowest at the base and widest at the 

 free end (figs. 13, 18 and 19). It is divided by three constrictions into four segments. 

 which gradually decrease in length, the foremost one being the longest. Besides, the 

 second one presents traces of a division into two. The whole surface of that curious 

 organ is covered with slightly curved spines or hooks, which are smaller and more 

 crowded on the first segment; hence they gradually decrease in number but increase 

 in size, those on the terminal segment being rather powerful. The arrangement of 

 the spines seems to be somewhat irregular. 



Moreover, the caudal appendage is remarkable for another singularity, its first 

 segment being furnished with a number of hollow bladders or säcks, which evidently 

 correspond to the cylindrical or fusiform tubes which cover the whole surface of the 

 caudal portion of other Priapulids, giving it a shrub-like appearance. In the only 

 specimen at my disposal the second segment al so was furnished with such a bladder 



(fig. 18). 



I think there can be no doubt that the bladders in question are remains from 

 a past epoch, when Priapulus horridus, devoid of spines or hooks, was provided with 

 a shrub-like caudal appendage, like other Priapulids. 



According to my views the caudal appendage armed with spines or hooks in 

 specimens of Priapulids ought to be looked on as a secondary acquisition not as an 

 original one. 



The oral aperture has its position as usual in the centre of the free end of 

 the introvert and is armed with teeth. By an accident the very small preparation 

 representing the armed parts of the mouth and oesophagus was löst, a few broken 

 teeth alone being left (figs. 15 and 16). On account of this accident I am unable 

 to state the true construction of the dentary apparatus. However, to judge from 

 the fragmentary remains, the shape of the teeth must have had a structure similar 

 to that of other Priapulids, or nearly so. Each tooth seems to have been provided 

 with a central larger spine and several small lateral ones. The fig. 15 with five 

 lateral spines on each side evidently represen ts a tooth from the oesophagus. 



The intestine descends from the oesophagus in an almost straight direction 

 to the rectum, which passes through the excentric opening of the muscular diaphrag- 

 matic membrane which separates the body-cavity from that of the caudal appendage, 

 and terminates in the anal aperture. With regard to this aperture, I have not been 

 able to state its true position, but very likely it should be situated on either side 

 on the genital pores and behind them, as is the case in Priapulus caudaius (fig. 17). 



The reproductive organs are two in number, large and filled up with well- 

 developed eggs (fig. 17). They are connected with the wall of the body by mesen- 

 teries, and their efferent ducts open posteriorly on each side of the nerve-cord. 



K. Sv. Vet. AkaJ. Handl. Band 47. N:o 1. 4 



