1911-12.] Structure and Affinities of Branchiomaldane viricenti. 7 1 
puerilis. In Branchiomaldane , hermaphroditism is associated with seden- 
tary habits (as in the case of the hermaphrodite Serpulids Spirorbis and 
Salmacina), and with small size and comparatively simple external form, 
and, may be safely regarded, as in the other cases mentioned above, as a 
secondary character. 
Branchiomaldane presents an interesting parallel to the Nereid Lycastis 
quadraticeps ; both worms are considerably smaller than their immediate 
allies ; they are hermaphrodite, and their ova are much larger than those 
of their dioecious relatives. Dr H. P. Johnson * has pointed out that in 
L. quadraticeps the increase in the size of the ova “ is not co-ordinate with 
complexity of organisation, or any real advance towards a higher plane 
of being, but rather the reverse ; . . . the macroogenous Polycheetes are 
all of puny size, comparatively simple organisation, and onef is herma- 
phroditic.” These remarks are in accord with the grade of development 
exhibited by Branchiomaldane, which, as compared with its ally Arenicola , 
has certainly not made “ any advance towards a higher plane, but rather 
the reverse.” 
The systematic position of Branchiomaldane may be summarised thus : 
the genera Arenicola and Branchiomaldane (with a single species, B. 
vincenti) together constitute the family Arenicolidae. Branchiomaldane 
is most nearly related to the ecaudate species of Arenicola ( ecaudata , 
Johnst. and branchialis, Aud. et Edw.), to young stages — about 10-12 mm. 
long — of which it presents some points of similarity in form and habits. 
But Branchiomaldane differs from these species of Arenicola in several 
important characters ; for instance, its branchial segments are bi-annulate 
and the setae and gills are borne on consecutive annuli ; its nephridia are 
reduced to two pairs, the second of which is considerably modified ; it is 
hermaphrodite and produces comparatively few but large eggs, and it does 
not possess septal pouches, statocysts, nor a nuchal invagination. Although 
the young stages of Arenicola above mentioned have, for a time, habits 
similar to those of Branchiomaldane, the former soon assume a more 
wandering mode of life, which they maintain henceforward ; whereas Bran- 
chiomaldane remains sedentary, and some of its structural peculiarities are 
no doubt the result of retrogressive changes associated with its tubicolous 
habits. 
* Biol. Bull. Wood’s Holl, vol. xiv. (1908), pp. 371-386. 
t Namely, L. quadraticejps ; Dr Johnson does not appear to have been aware of the case 
of Branchiomaldane. 
