40 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the nephridia have disappeared from the anterior somites ; the coelomic 
epithelial cells surrounding the nephridia are vesicular in character ; 
a vascular network on the gut has broken down to form a sinus ; and 
there are no dorsal pores. 
As the home of the Rhinodrilidae is America, the occurrence in 
England of a member of the family is very striking, but the Thames is 
visited by all sorts of traffic, and the cocoons may have been brought 
over with timber, or among the roots of some water-plants, such as 
Anacharis alsinastrum which has increased in our rivers. 
One point in which Sparganophilus is very remarkable is the super- 
ficial position of the sperm-duct, which becomes subepidermic ; such 
a position for the duct is unknown in any Oligochaete. Dr. Benham 
suggests that this is an archaic feature, the primitive sperm-duct having 
opened externally in the segment following the funnel, and a groove 
having appeared to carry the spermatozoa further back ; later on this 
groove sunk into the epidermis, became a canal, and so gave rise to the 
long duct so usual among earthworms. 
Eyes of Hirudinea.* — Herr B. L. Maier describes the minute struc- 
ture of the eyes in Hirudo, Aidostomum , Nephelis , Clepsine, and Piscicola. 
He is convinced that they are eyes. They consist essentially of a 
cellular pigment layer and a retina of large strongly refracting cells. 
Within the latter there is a capsule of modified plasma which is usually 
invaginated as a knob or ridge. This capsule is probably homologous 
with the rod-structures of the cells which are sensitive to light in other 
eyes. Each cell is connected with a fibre from the optic nerve. In 
Nephelis, Clepsine , and Piscicola the nerve enters the eye from in front ; 
in Hirudo and Aulostomum the main branch enters the posterior wall 
and extends axially through the eye, while a second branch unites ante- 
riorly and ventrally with the foremost cells. 
Blood-pigment of Gephyrea-t — Dr. A. B. Griffiths has a note on the 
red pigment with respiratory properties which is found in the blood of 
Sipunculus and Phascolosoma. and was called hmmerythrin by Krukenberg. 
He finds that the empirical formula is C'427H76 1 N lg5 EeS 2 0 1 53 ; the pigment 
exists in an oxidized and a reduced condition. This is the fourth 
respiratory pigment found in Invertebrates which contains iron. 
B ■ Nemathelminth.es. 
Muscle and Nerve of Nematodes.! — Dr. E. Rohde reports some 
observations on the histology of Ascaris megalocephala and A. lumbri - 
coides. The cortical portion of the coelomyarian muscle-cell is divisible 
into two different substances, the specially contractile muscular columns 
and the interfibrillar mass. The former are bands, generally of homo- 
geneous appearance, which are set radially in the cortex of the cell, and 
alternate regularly with the interfibrillar mass. This latter is the con- 
tinuation of the central medullary substance, and consists of a homo- 
geneous hyaloplasm and a spongioplasm formed of a complicated plexus 
of fibrils and very greedy of colouring matters. The muscle cell of the 
* Zool. Jalirb., v. (1892) pp. 552-80 (1 pi.). 
t Comptes Rendus, cxv. (1892) pp. 669 and 70. 
X SB. K. Akad. Berlin, 1892, pp. 515-26. 
