NEMERTINES OF PLYMOUTH SOUND. 5 
is much the better, and in spite of the absence of any striking 
structural differences between the genera Oerebratulus and Micrura, 
and only that of the caudal appendage between these and Lineus, 
this arrangement is much more convenient and natural. 
With regard to the spawning periods of the various species my 
observations are not at present very complete. It may, however, be 
stated generally, that during the whole year some one or more 
species are breeding, and I was considerably astonished to find a 
large number of species with ripe generative products from late 
summer to the middle of December when I left Plymouth. During 
this period my specimens of A. dissimulans laid several batches 
of fertilized eggs, and all the species of Tetrastemma and many 
Schizonemertines were ripe, as was also the parasite Malacobdella. 
The tow-net, too, contained many pilidia of different species, as well 
as numbers of Cephalothriz larve. The presence of the latter was 
surprising, as I did not meet with any ripe adults later than 
August. 
I have nothing to add to the observations of Joubin on the ver- 
tical distribution of these forms, with which my own substantially 
agree, 
I have not attempted to give a list of the synonyms ; a few only 
are given in the case of especially interesting species, or where there 
have been any recent changes in nomenclature. 
The definitions of the different groups are those of Burger. 
Order 1.—PROTONEMERTINI, Biirger. 
Brain and lateral nerves lie outside the muscular coat of the body- 
wall, either in the epidermis or beneath the basement membrane. 
Body-wall consists of epidermis and of a circular and longitudinal 
muscular layer. Mouth behind brain. Proboscis without a stylet. 
Family CARINELLIDAS (McIntosh). 
Genus CARINELLA, Johnston. 
1. C. potymorpHa, Renier, Hubrecht. 
VALENCINIA SPLENDIDA, de Quatr. 
TUBULANUS POLYMORPHUS, Renier. 
CARINELLA ANNULATA (pars), McIntosh. 
Only one specimen has been obtained. It was dredged in 
25 fathoms off Stoke Pomt on March 22nd, and its occurrence 
