THE VOYAGE OF H.M.S. CHALLENGER. 
1 >'< 
these specimens were not quite mature, the accessory nidamental glands being in fact 
little developed and scarcely visible in immature individuals.^ 
5. Laying or deposition of the eggs. — The manner in which the eggs are deposited is 
unknown. We know, however, that the eggs contained in the oviduct are rather large 
(Fig. U; PI. IV. fig. 3, ov.) and with abundant vitellus, as the structure of the ovarian 
ovule shows, provided with a vitelligenous follicle with multiple folds in the interior of 
the eggs (Fig. V.). On the other hand, we may also infer that the eggs when once laid 
are enveloped in a rather thick coating, since Sph'ula is provided not only with an oviducal 
gland, but further with properly so-called accessory nidamental glands. 
VII. Classification. 
.\ dozen of difterent specific names have been applied to the shells of the genus 
Spinda. But even in the opinion of a conchologist^ : “ it is impossible to determine 
to which of the species (if they are distinct) the names applied to the shells belong.” 
On the other hand, the number of complete specimens of Spirula, which have been 
fully examined and described, is exceedingly limited (see Introduction). It results from 
this that there arc no means of attaching a definite value to the names originally imposed 
or adopted, from the want of sufficiently distinctive characters. 
In a provisional way I propose to consider the Challenger specimen as the type of 
the sjHJcies Spirula peronii ; the specimen described by Owen in 1879 as the type of 
the 8iK*cies Spirula australis { = lsevis, Gray), to which the “Blake” specimen appears 
to Ixj related ; and lastly. Professor Giard’s specimen as the type of the species Spirula 
retietdata { = vulgat'is, Leach). So that we may establish provisionally the following 
table, which further knowledge and a comparison of future specimens may possibly 
modify : — 
1. No distinct furrow separating the mantle from the disk. Spirula peronii, 
Lamarck (PI. I. figs. 1-4). 
2. Terminal disk separated from the mantle by a deep furrow. 
A. Sub-epidermic reticulation not very distinct. Spirula australis, Lamarck 
(PI. II. figs. 1-3). 
B. Sub-cpidemiic reticulation very marked. Sjn'nda reticulata, Owen (Figs. 
A,C, I.J, N). 
' Rrock, o]t. I'it., ji. 72. 
Gray, Catalogue of the Mollusca, i». 115. 
