522 SUMMARY OF CURRENT RESEARCHES RELATING TO 



same way developed from A. laoustris. This has occurred in the Canal 

 du Midi, andjis an instance of present-day forms whose origin is quite 

 modern and produced by natural causes — an instance of evolution per 

 solium, -v There are no transitional forms. 



Segmental Veins in Amphioxus.* — ■ Boris Zarnik describes the 

 segmental veins of the lancelet and their relation to the ductus cuvieri. 

 There seems to be no doubt that the lancelets exhibit very primitive 

 relations in their vascular system, as in other systems. These conditions 

 represent, as the author shows, a transition stage between the differenti- 

 ated circulatory system of Craniota and the simple loops and sinuses in 

 Invertebrates. The paper is accompanied with an exceptionally fine 

 figure of the posterior peribranchial cavity of an adult female lancelet. 



INVEBTEBRATA. 



Mollusca. 

 a. Cephalopoda. 



"Albatross" Cephalopods.t — W. E. Hoyle reports on the cephalo- 

 pods collected in the tropical Pacific by Alexander Agassiz on the 

 " Albatross " Expedition. The collection consists of thirty species (six 

 new) distributed in nineteen genera, one of which {Froekenia) is new. 

 Another {PterygioUuthis) was first found by the " Albatross," but its 

 publication has been anticipated by the description of an immature 

 example by H. Fischer. In a smaller collection made among the Pacific 

 islands, which contained thirteen species, there was a new genus, Cirro- 

 brachium. The new genus Froekenia is allied to CirroUuthis, with paired 

 fins at the sides, but with no connecting membranes between the arms. 

 In the new decapod Cirrobrachium, based on a head and arms, there is a 

 row of filaments along the outer or ventral side of each arm, except those 

 •of the fourth pair. An appendix contains an account of the luminous 

 ■organs of PterygioUuthis giardi and Abraliopsis hoylei. 



Structure of the Heart in the Common Octopus.:}: — F. Marceau notes 

 that the descriptions of the structure of the heart in cephalopods are 

 somewhat discrepant. He has made a histological study of the heart of 

 Octopus vulgaris. 



The striated fibrils composing the cortex are in some respects re- 

 markable. They are slightly larger than those of the cardiac muscle- 

 fibres in Vertebrates ; but the muscular discs of the fibrils are more than 

 twice as long as those of corresponding fibrils in Vertebrates. 



The heart is lined by a very delicate endocardium, formed by an 

 endothelium with very minute and much-flattened nuclei, below which 

 there are connective cells at wide intervals. . 



Receptaculum Seminis and Nuptial Combat in Octopus.§ — W. 



Bergmann has found in Octopus de filippii a receptaculum seminis which 



* Anat. Anzeig., xxiv. (1904) pp. 609-30 (1 pi. and 7 figs.). 



t Bull. Mus. Zool. Harvard, xliii. (1904) pp. 1-71 (10 pis. and map). 



X Comptes Rendus, cxxxviii. (1904) pp. 1177-9. 



§ SB. Ges. Nat. Freunde Berlin, 1903, pp. 104-9 (3 figs.). 



