[ 77 ] 



III. Oh the Structure and Affinities of Echiurus unicinetus. 

 By Alice L. Embleton, B.Sc. {Communicated by JProf. G. B. Howes, Sec. L.S.) 



(Plates 7 10.) 



Read Ttb June, 19(i0. 



J HE observations recorded in this paper were made by me in the Zoological Laboratory 

 of the Royal College of Science, London, during January, Pebruary, and March 1900, 

 under the direction of Professor Howes and Mr. M. E. "Woodward, to both of whom I 

 owe a debt of gratitude for their generous help and advice. 



The material was obtained by Professor Howes from Professor Mitsukuri, of Tokyo, 

 through the kindness of Mr. H. Lyster Jameson, who had intended to rejiort upon it in 

 his recently published paper in the Naples ' Mittheilungen,' but for want of time had been 

 prevented from so doing. 



The specimens, numbering between 90 and 100, were in alcohol, and had been 

 preserved in corrosive sublimate. On the whole they were in very good condition, 

 though much contracted, resiilting in great variability of shape both as regards the 

 entire body and the different organs ; in several individuals, parts of the alimentary canal 

 were forced out through bursts in the body-wall, presumably caixsed by sudden and 

 violent contraction. To a large extent these post-mortem changes obscured many 

 observations which, on fresh or uncontracted material, could have been made with 

 greater ease and certainty. 



Doubtless this is the species mentioned — though not named specifically — by Willemoes- 

 Suhtn * as occurring on the Japanese coast, where apparently it lives in great abundance, 

 for he says : " Ein Echiurid der den Eischern als Koder dient und wohl in Schlamm 

 dicht am Ufer vorkommt. Der S-Jt Zoll lange Wurm stimmt ganz mit den Merkmalen 

 der Gattung Echiurns iiberein, hat aber hinten nicht zwei Hakenkriiuze, sondern nur 

 einen." 



The average length of the body is about 7 oi' 8 cm. ; all the specimens are narrowest 

 at the posterior end, widening out gradually, as a veritable sac, between this and the 

 ])rol)oscis. The term " proboscis " is used, though that organ is, in all, represented 

 merely by a bluntly-pointed prte-oral lobe of triangular outline (PI. 7. figs. 1-2, pi).) ; 

 it cannot J^e doubted, however, that this is due to its state of contraction, for in cutting 

 a series of microscopic sections of the anterior end of the body there was nothing 

 to suggest that the proboscis was missing, as is so often the case with the Bintish 

 iovm, Echiurus Fallasid {Guevin), called "E. vulgaris" hy Eorbes, Eorbes & Goodsir, 

 Sars, O. Schmidt, and Metzger. 



* " Von der Vhallenr/er Expedition, lirieff von K. v. Willemoes-Suhm an C. Th. v. Siebold, vii.,'" Zeitschr. wiss. 

 Zool. Band xxvii 1876, p. cii. 



SECOND SERIES. — ZOOLOGY, VOL. VIII. 12 



