SCOLECIDA. 637 
10. This genus wants the characteristic head and ventral setae of Desmo- 
scolcx. This form at first looks Ichthydian, but is truly Nematoid. 
Eulrntrichtis Jiliformis, g. and sp. n., GreefF, 1. c. p. 117, Taf. 7. figs. 1-4. 
Only females of this remarkable form were found. It is about 8 millims. 
in length ; body long, thread-like, covered with very fine setae or hairs j 
mouth funnel-shaped; intestine simple. — North Sea. E. phalacrusy 1. c. 
p. 118, Taf. 7. figs. 6-8, Lanzarote. 
TURBELLAIIIA. 
McIntosh (1. c.) shows the essential difFerenees which exist 
between tlie Ommatopleans and the Borlasians, from the skin 
even to the microscopical structure of the proboscis. These 
names are provisionally used because the majority of these soft 
animals group themselves round two centres, represented respec- 
tively by the common 0?nmaloplea alha and Borlasia olivacea. 
The minute structure of both these species is described in great 
detail, taking them as types of each group ; and the differences 
that are met with between these and allied species arc pointed 
out. 
Metschnikoff {L c.) concludes his observations on the de- 
velopment of the Nemcrtcans by stating that on glancing at 
the special developmental history of the Nemerteans, which are 
formed with the pilidium, the following principal facts are ob- 
served: — 1. The first appearance of the body of the Nemertean 
is under the form of two pairs of infolding of the skin, which 
become converted, not only into the bodies of the worm but also 
into the very amnion surrounding them. 2. Moreover two central 
vesicles are formed, which later become amalgamated with the 
lateral vessels. 3. The four lamellae arising from a portion of the 
infolding of the skin which represents the future germ- streaks 
(for so, after Leuckart, we will call the cup-shaped bodies) arise 
from two germ-folds placed together ; of these, the outer fold 
forms the epidermis of the central nervous system, while the 
inner and thinner fold forms the muscular system. 4. The geFm- 
streaks produced by the growth of the four layers (Scheiben) re- 
present the future ventral surface, with the cephalic portion of 
the Nemertean, whilst the dorsal covering is formed afterwards. 
5. The proboscis appears in the form of a simple infolding of the 
fore end of the germ-streak. Vide also the remarks of the same 
author in Bull, de TAcad. Imp. d. Sc. St. Petersbourg, t. xiii. 
No. 3, p. 288. 
