49 



long receptacular duct opens (Fig. II, r.d.). The receptaculum 

 seminis is small and globular. The oviducal portion of the common 

 duct (Fig. II, ov.), is a wide tube folded twice npon itself. The 

 penis is a large twisted organ, aud in length considerably exceeds 

 the same organ in any other species of the genus (Fig. II, p.). 

 At a point about one- sixth of its length from the genital opening 

 it gives off a blunt flagellum ; it then expands into a sac-like portion, 

 thence it continues for a short distance as a straight tube, and then, 

 making a sharp turn, becomes folded upon itself, at its junction with 

 the vas deferens (Fig. II, 'V.d.). This latter is a narrower tube, 

 leading into the prostatic portion of the common duct, which is longer 

 and narrower tlian in Af/r. gloJxjs/is. There is a large oval albumen 

 gland. The hermaphrodite gland (Fig. II, h.ffl) is somewhat pyriform 

 in shape, and opens into a sliort convoluted duct. 



I have much pleasure in associating with this interesting species 

 the name of Mr. E. C. L. Perkins. 



The differences in the form of the reproductive organs of Af/r. 

 fflohosus and At/r. Pcrkinn are fairly well marked, and easily 

 distinguish them from their nearest allies. The question, however, 

 of how far the form of the penis, free oviduct, etc., vary in a known 

 species, is one of great interest, and must sooner or later be investi- 

 gated. Dr. J. F. Babor, of Prague (2), has published some interesting 

 notes in connection with this subject, and it is greatly to be hoped 

 that he may find opportunity for further extending his researclies. 



The species of AgrioUmax, recently described as new by Simroth 

 (12), seem to me to be established on minute variations common 

 to all mollusca, as do those figured and described by Babor and 

 Ivostal (1). Possibly later investigations may prove that in this genus 

 the reproductive organs are subject to a wide range of variation, 

 and that recourse will have to be had to the general anatomy. In 

 A. Soiverhijii and A. (jagates the only variations in the generative 

 organs I have been able to find are in the form and number of the 

 accessory glands and the constrictions in the sperm-duct (4). 



3. Amalia gagates (Drap.). 

 The specimens of A. gagates which come from Maui differ slightly 

 from those I have examined from various European localities. The 

 groove on the mantle terminates anteriorly as a sharp point (Fig. Y) ; 

 and on the head, in the mid-dorsal line, there is the peculiar groove 

 so conspicuous in A. rohici, Simr. Internally there are also slight 

 differences in the form of the sperm-duct (Figs. Ill and IV, s^i.d.) 

 and accessory glands. Probably all these characters are due to 



VOL. II. — ArRiT,, 189fi. 4 



