ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
31& 
chyma, or, in higher forms, on the epithelium lining the genital sacs. 
An efferent duct is not formed until maturity. Several species of 
Geonemertes , Prosadenoporus, and probably Prosorhochmus , are herma- 
phrodite ; a few species of Tetrastemma are protandrous hemaphrodites ; 
ProsorJiochmus , a freshwater Tetrastemma , and a species of Linens are 
viviparous. 
In the physiological chapter the author notes, inter alia , his conclu- 
sion that the reserve stilets really replace the functional stilets, that 
Cerebratulus , Langia , and Drepanophorus owe their capacity for swimmin 
to the neurochord cells, that the cerebral organs test the surroundin 
medium, and that the head grooves are tactile. 
Two polar bodies are extruded ; fertilisation may be internal or 
external ; segmentation is total and equal (unequal in Munopora vivipara ) ; 
gastrulation is complete or partial; development is direct in Meta- and 
Mesonemertini, usually indirect in Heteronemertini ; six species of 
Pilidium larvte are distinguished. 
The systematic portion is very full ; 164 species (74 established by 
the author) are described ; three new genera — Hubrechtia , Nemertopsis, 
and Prosadenoporus — are constituted, and others are reconstituted ; 
Hubrecht’s Palaeo- and Schizonemertini are rearranged as Proto-, Meso-, 
and Heteronemertini. 
Burger’s scheme of relationships is as follows : — 
Lineidae 
Eupolidae 
Heteronemeutini 
Hubrechtia 
Carinina 
Protonemertini 
Ancestral forms 
(related to Turbellaria) 
Holorhynchocoelomia 
Prorhynchocoelomia 
Pelagonemertes 
Metanemertjni 
Ceplialothrix 
I 
Carinoma 
Mesonemertini 
to to 
