MOLLUSCA OF INDIA. lOS 



figs. 1, 1 a, 1 h. Further observation of these structures shows that 

 the position of the cervicorn processes, and those more feathery and 

 elongate, is well-defined : the latter are attached at the base of the 

 "flume" or gutter (Plate XCIIE. figs. 1 5, 1 c) ; the former at 

 the head, where the sac or capsule is situated. In Girasia the sides 

 of the flume are straight, and the short spines set at close intervals, 

 which are seen in other genera, are absent. I give also a copy 

 (on Plate LXXXVIII. fig. 1 c) of fig. 5, pi. xxvii. P. Z. S. 1880, 

 representing the segmentation of the foot in this genus, and which 

 is described on p. 219, Vol. I. of this work. This segmentation 

 appears to be structural, not due to muscular contraction, which 

 would be less regular ; these segments across the sole of the foot 

 correspond to, and are continuous with, the main segments of the 

 pallial fringe or margin of the foot. Having lately dissected 

 specimens of G. hookeri, I am able to supplement my previous 

 description in Vol. I. by further details. When the shell-lobes are 

 cut and laid back and the shell removed, the visceral sac presents 

 no coil whatever (see Plate LXXXVIII, fig. 2 e), a character to be 

 noted when this genus is compared with Damayantia, Parmarion, 

 and Microparmarion of the Malay Archipelago (see Plates LXXIII.- 

 LXXV., Part VIII.), or with Africarion of S. Peninsular India 

 (Plate LVII., Part VI.). On the left side of the visceral sac two 

 close parallel lines may be traced, which correspond to a narrow 

 raised ridge on the outside of the mantle, more or less conspicuous 

 in life (vide Plate LX.) ; this occupies a position more analogous to 

 the keel of the shell, for it is not related to the line of division 

 between the shell- and mantle-lobes, beyond running somewhat 

 parallel with it, but inside it. 



As the position of the main muscle-attachments is an interesting 

 point in the anatomy of the slug-like species, I have paid attention 

 to it ; no part of their structure can be overlooked, for all becomes 

 valuable from a morphological point of view. Simroth, Pilsbry 

 and Vanatta have shown this. It is well to quote a paragraph in a 

 paper by the two latter named naturalists (" A Eevisiou of the 

 North-American Slugs ") * : — 



"That ' system ' is, in fact, an epitome of the total structure, as 

 well as, with certain distortions, a phylogeuy of organisms; we have 

 freely used characters from all organs in which we found differ- 

 entiation, in the construction of our scheme of family, subfamily, 

 and generic classification." 



As exposed to view on dissection, the dart occupies the right-hand 

 side of the animal; the penis is on the top of the neck. The main 

 body-cavity does not extend back into the foot; there is a distinct 

 separation between this and another cavity on a plane below the 

 periphery of the shell, Plate LXXXVIII. figs. 2 a, 2 h. The 

 upper or visceral cavity is again divided diagonally into anterior and 

 ])osterior chambers. The former is the branchial cavity with the 

 heart and renal organ ; the latter is occupied by the intestinal folds 



* Proc. Acad. Nat. Sciences of Philadelphia, 1S98, p. 219. 



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