Miscellaneous. 383 



males could only be complementary males, the existence of which 

 is by no means probable. 



2. The difference noticed between the embryos of the same species 

 is due to the fact that the embryo when scarcely hatched undergoes 

 a first metamorphosis. Sometimes, even, this metamorphosis is ac- 

 complished so rapidly that embryos of two different forms are ex- 

 pelled simultaneously from the maternal organism in which the 

 incubation has taken place. As the differences between the embryo 

 just issuing from the egg and that which has undergone a first moult 

 are altogether very slight, this moult has passed unobserved. It is, 

 on the contrary, very manifest in the Cirripedes proper, as in Lepas, 

 where the difference is enormous and very curious. 



The supposed primitive ovary indicated with doubt by M. Gerbe, 

 and with certainty by M. Balbiani, is, as I have formerly pointed out, 

 a mass of cells, which after the second moult becomes differentiated 

 to form the six pairs of natatory feet, homologous with the cirri of 

 the Cirripedes. 



An error similar to that of M. Gerbe has been made by Professor 

 Semper, who describes as furnishing a larva of a very peculiar form 

 a Peltogaster of the Philippine Islands, of which he has evidently 

 observed the embryos only after the first moults, when they already 

 affected the Cypridine form (Zeitschr. fiir wiss. Zool. xiii. pi. 38. 



fig. 3). 



I may add that the larvae of the Rhizocephala are very imperfectly 

 known. I can nowhere find a description of their trilobate rostrum, 

 comparable to that of the embryos of Cirripedes (an acute median 

 lobe and two rounded lateral lobes). M. E. van Beneden, who has 

 recently paid attention to these animals, does not notice this ap- 

 paratus ; nor does he mention the voluminous frontal glands, the 

 product of secretion of which traverses a canal opening at the trifid 

 extremity of the lateral anterior appendages of the carapace. He 

 is equally silent respecting the organs situated on each side of the 

 middle part of the animal, and generally coloured yellow or red 

 (primitive kidneys ?). He denies the existence of the muscles ; and 

 yet nitric acid brings to view most distinctly striped muscular fibres, 

 the arrangement of which is interesting to study. On the other 

 hand, he admits the existence of a mouth situated very far back. 

 This mouth does not exist in any of the species examined by me 

 (Saccalina carcini, Peltogaster paguri, and P. Prideauxii). It is 

 possible that this organ exists in other types, especially in the Saccu- 

 lina of Xantho florida, in which M. Gerbe asserts that he has met 

 with a pretty highly organized digestive tube. — Compies Beiidus, 

 July 6, 1874, p. 44. 



Notice of some new Freshwater lihizopods. By J. Leidy. 



Prof. Leidy remarked that, besides the ordinary species of Amoeba 

 which he had observed in the vicinity of Philadelphia, he had dis- 

 covered what he suspected to be a new generic form. It has all 

 the essential characters of Amoeba, but. in addition, is provided 



27* 



