1905-6.] Echinorhynchus antarcticus and its Allies. 
445 
is unique, there is a remarkable agreement in the distribution 
of spines upon it and upon E. hystrix. With this species it 
agrees also in the characters of the sub-cuticular canals. It, how- 
ever, differs from it in the number and size of rostral hooks, in the 
absence of the false neck,* in the shape and size of the embryos, 
and in the number of testes and relative sizes of the sexes. With 
reference to E. piriformis , the shape comes nearest to that of 
E. antarcticus, but the distribution of body-spines is different. 
They agree in the absence of a neck region, and differ in the 
nature of the sub-cuticular canals and in the number and rows of 
rostral hooks. Similar observations apply to E. striatus, and all 
the points are characters of specific significance. 
The rostrum in E. antarcticus is larger in proportion to size of 
body than that of the others, and the number of rows of hooks 
much greater. The size of the shelled embryos also is distinctive. 
They range from '057 mm. to '19 mm. in length, and even within 
the same animal considerable variation may be met with. De 
Marval invariably speaks of the ova (“ oeufs ”) as triple-shelled, 
but his figures are those of embryos in which both ectoderm and 
endoderm are differentiated, and it is with these that the embryos 
of E. antarcticus are compared in the foregoing table. 
EXPLANATION OF TEXT-FIGUKES. 
r. = rostrum, f.n. — false neck. 
Figs. 1, 2, and 3 from de Marval. 
Figs. 1, 3, and 4 are magnified about 10 times; fig. 2 rather 
more. 
* De Marval thus distinguishes the neck and false neck: — “Nous appelons 
‘ cou ’ tout organe nettement delimite du corps, soit par un etranglement, soit 
par une ligne de demarcation bien nette, contenant totalement ou en partie 
seulement la poche qui vient s’inserer a son bord anterior. Le cou, non 
invaginable, supporte a son extremite le rostre, qui, la plupart, du temps, 
semble ne former avec lui qu’un seul et meme organe. . . . Nous appellerons 
par contre ‘ faux cou ’ toute partie delimitee ou non du corps, nue ou garnie 
de petits aiguillons, et n’etant somme toute que le corps proprement dit effile 
en avant, ou la base du rostre tres allongee. Nous parlerons done, dans la 
suite, suivant le cas, d’un cou et d’un faux cou, nus ou armes.” 
