28 
THE VOYAGE OE H.M.S. CHALLENGER. 
these specimens were not quite mature, the accessory nidamental glands being in fact 
little developed and scarcely visible in immature individuals. 1 
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. R; 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 Spirula, is provided not only with an oviclucal 
gland, but further with properly so-called accessory nidamental glands. 
VII. Classification. 
A dozen of different specific names have been applied to the shells of the genus 
Spirula. But even in the opinion of a conchologist 2 : “ 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 are 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 species Spirula peronii ; the specimen described by Owen in 1879 as the type of 
the species Spirula australis l^—lsevis, Gray), to which the “Blake” specimen appears 
to be related; and lastly, Professor Giard’s specimen as the type of the species Spinda 
reticulata ( = vulgaris, 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 
(PL II. figs. 1-3). 
B. Sub-epidermic reticulation very marked. Spinda reticulata, Owen (Figs. 
A, C, I, J, N). 
1 Brock, op. tit., p. 72. 
2 Gray, Catalogue of the Mollusca, p. 115. 
