46 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
excitation of tlie cerebral surface. It appears to be clear that there are 
in the circumoesophageal ganglia chromato-constrictor centres which, 
when put into activity, can paralyse the chromato-dilatator centres. In 
all the experiments where chromato-constriction had been suppressed, 
the cerebral ganglia had been first made unable to act. 
It may, therefore, be concluded that the inhibiting centres of the 
chromatopliores are localized in the cerebral ganglion, and that it is 
the direct action of these centres on the chromato-dilatators that produces 
the momentary paralysis of the dilating muscles, and the resulting 
pallor. 
For chromatophores, as for blood-vessels, the inhibition of the mus- 
cular fibres is not effected directly, but by the intermediation of nerve- 
centres. 
Bilateral Hectocotylization in Eledone cirrhosa.* — Dr. A. Appellof 
calls attention to a specimen of this Ceplialopod, in which the third arm 
on the left as well as on the right side is hectocotylized. It is exceed- 
ingly rare for more than one to be thus modified, but there are, in the 
case under consideration, no other abnormalities either in the arms or in 
the reproductive apparatus. 
y. Gastropoda. 
Neotsenioglossae.t — Herr B. Haller describes Triton , Dolium, Strom - 
bus , and other “ longicommissurate ” Neotacnioglossas of the “Vettor 
Pisani” collection. The general characteristic is the length of the 
cerebro-pedal, pleuro-pedal, supra-intestinal, and sub-intestinal com- 
missures. The most primitive family is the Tritonidae, with the genera 
Banella , Triton , and Persona. As chief characteristic of the family the 
author notes the elongated pedal ganglia. The Dolideac come next, 
between Tritonidae and Strombidae, characterized by the complete fusion 
of cerebral and pleural ganglia and by the strong development of the 
fore-gut. The genus Cassidaria is more primitive than Dolium. In 
the family Strombidae there is a striking structural similarity between 
Strombus and Bostellaria, and the genus Xenophorus, which the author 
previously placed near Naticidae, must be included here. The Ptero- 
ceridae seem to be nearly allied to Strombidae, but the author has only 
investigated the nervous system of Ctenopus. 
Absence of Male Reproductive Organs in Two Hermaphrodite 
Molluscs. J — Mr. W. E. Collinge has found in two species, normally 
hermaphrodite, viz. Helix aspersa and Arion intermedins (?) an absence of 
male reproductive organs, and he urges that these facts should be con- 
sidered in view of the generally accepted doctrine that hermaphroditism 
was the primitive state among multicellular animals. 
Dorididse.§ — Dr. R. Bergh has some critical notes on Doris stellata 
Cuv., with which Jorunna Johnstoni is identical, and gives an account of 
its anatomy. A full account is given of D. acutiuscula which has scarcely 
been mentioned since the time of Moller ; there are also anatomical notes 
on two species from Port Jackson first described by Anga: — Chromodoris 
Bennetti and G. festiva. 
* Bergens Mus. Aarbog for 1892 (1893) No. 1, p. 14. 
f Morphol. Jahrb., xix. (1893) pp. 553-91 (4 pis.). 
I Journ. Anat. and Physiol., xxvii. (1893) pp. 237 and 8. 
§ Abh. Zool. Bot. Ges. Wien, xliii. (1893) pp. 408-20 (1 pi.). 
