208 
ZOOLOGICAL LITEllATUllE. 
Jeffreys, J. G. Remarks on Stilifer, a genus of qnasiparasitic 
mollusks, with particulars of the European species. Ann. 
& Mag*. Nat. Hist. xiv. pp. 321-334. 
Two specimens of Stilifer turtoni have been observed alive ; they 
always occupied the upper surface of an Echinus, near the vent, 
whilst Montacuta substriata inhabits the under surface near the 
mouth ; they are not fixed, but creep about and seem to pass 
their whole life on the Echinus; there is no predilection for a 
particular species of Echinus. A description of the animal 
and shell in its adult and young state is given. — The author 
knows 16 species. 
Cythnia aster iopkila, Carpenter, Ann. & Mag. Nat. Hist. 1864, xiii. p. 478. 
From Cape St. Lucas, California. 
Entoconcha. Although there is no other affinity between this 
curious animal and Stylifer than the similarity of parasitic life, 
we follow the arrangement of Messrs. Adams, and insert here an 
abstract of a memoir by A. Baur, Beitr'age zur Naturgeschichte 
der Synapta digitata — Dritte Abhandlung : Die Eingeweide- 
Schnecke [Helicosyrinx parasita) in der Leibeshohle der Synapta 
digitata” Nov. Act. Ac. Cses. Leop. Carol. Nat. Cur. xxxi. 1864. 
By the organization of the adult and by its parasitic life in the 
interior of another animal, this mollusk is distinguished not 
only from Stylifer , but from any other known family of Gastero- 
poda. 
The author devoted two months, at Zaule near Trieste, to ob- 
serving and investigating this animal, which, years ago, had been 
the wonder of Joh. Muller ; but in consequence of its rarity (it 
does not occur more than once in 100 individuals of Synapta), 
he has not had the good fortune to discover new facts with 
regard to its development. However, he came to the conclusion 
that the seeming insertion of the shell-bearing bag ” in the 
cephalic part of the Synapta, where also the genital organs are 
situated (as observed by Muller), is only the result of the violent 
contractions of the Synapta during capture, and that, therefore, 
the idea of a genetic relation between Synapta and the ‘‘ shell- 
bearing bag ” must be abandoned. He thinks that the bag is 
to be regarded as a distinct, entire individual, belonging to the 
Nudibranchiataj and reduced by retrogressive metamorphosis to 
a kind of bag containing, besides the well-developed male and 
female organs of generation, a blind intestine only. He creates 
for it the name of Helicosyrinx parasita, as, in his opinion, that 
of Entoconcha cannot be applied to an animal which, in an adult 
state, is without shell. The young ones are provided with a 
shell, like those of all other Nudibranchiates, and pass the first 
period of their existence in the abdominal cavity of Synapta ; in 
consequence of the rupture which so frequently takes ph'u;e in 
Synapta, they become free, and- are thus enabled to immigrate 
