340 SUMMARY OF CURRENT RESEARCHES RELATING TO 
describes nine species of Canthocamptus , of which one ( C . bidens ) is new, 
and his list also includes Nitocra hibernica Brady, Ophiocamptus Sarsii 
Mrazek, and Ectinosoma Edwardsi Richard. 
Vermes. 
a. Annelida. 
Development of Ophryotrocha.* — Dr. F. Braem gives an account of 
the development of Ophryotrocha puerilis, a small Polychsete, “like a 
many-jointed Trochophore, with a ring of cilia round the middle of each 
segment.” His specimens were larger than those described by Claparede, 
Metschnikoff, and Yiguier ; they had 30-35 segments with parapodia 
and a length of 10-12 mm. The frontal segment bears two pairs of 
antennae with tactile hairs ; the head also shows two pairs of ciliated 
grooves ; the eyes resemble those of a Polygordius larva. Septa begin 
between the third and fourth segment, and occur regularly thereafter ; each 
of the posterior segments bears dorsally a pair of knob-like glandular 
swellings projecting externally; there is a short proctodaeum. The 
sexes are separate, the males smaller and thinner than the females. A 
case of hermaphroditism was also observed. 
The ovaries lie on the posterior wall of the septa, underneath the gut, 
on each side of the ventral vessel. Among the ovarian cells there is an 
interesting division of labour, for some become large, nutritive cells, dark 
when preserved, and very rich in chromatin, while the others form the 
smaller ova. There appears to be a sort of competition among the ova 
for association with the nutritive cells, which are in the minority. Each 
successful ovum liberated into the body-cavity is associated with a 
nutritive cell much larger than itself, but gradually the proportions are 
reversed. Dr. Braem has an interesting comparative discussion of the 
relations between ova and nutritive cells. The state of affairs in Piscicola 
closely resembles that in Ophryotroclia. 
The testes lie like the ovaries, and arise from a double longitudinal 
row of primitive mesoderm cells above the nerve-cord. These rows have 
their origin in the vegetative zone of the last segments, and the most 
mature testes are thus the most anterior. Spermatogenesis appears to 
be effected by direct division, and no polyplast stage was to be seen. 
Dr. Braem has also made some observations on regenerative pro- 
cesses. The vegetative zone of the anal segment is the seat of the 
formation of new segments. After injury, regeneration begins at that 
spot of the wounded surface which is nearest the tail end, and progresses 
centripetally. The further forward the cells are the less is their 
regenerative power. If the hind end be cut off, the first product of 
regeneration is a new anal segment with a new vegetative zone. Further 
defects are then made good centrifugally ; first the anterior and then the 
posterior segment are repaired. No copulation nor process of fertiliza- 
tion was observed. The ova issue by simple clefts of the body-wall 
between the parapodia, and were laid, surrounded by mucus from the 
ectoderm cells, on the glass sides of the aquarium. Two polar bodies 
are given off immediately after laying. The first cleavage is meridional 
* Zeitschr. f. wiss. Zool., lvii. (1893) pp. 187-223 (2 pis.). 
