226 Mr. W. D. Roebuck on the 



and in the sculpture of the body, as well as in the coloration 

 of the foot-sole and the body and shield j and, altliough 

 some of these differences are individually not great, yet 

 the sum or aggregate of them affords sufficient ground for 

 considering L. cinereo-niger as entitled to rank as, at the very 

 least, an incipient species, and for justifying malacologists in 

 awarding to it the speciHc or subspecific rank which many 

 authors give it. 



To take the differences which exist, and first those in the 

 anatomy of the genitalia. The importance of the reproductive 

 organs of the Mollusca as a criterion for the distinction of 

 species is universally recognized, and an examination of the 

 very careful and accurate MS. figures of the genitalia of many 

 individuals of both L. maximus and L. cinereo-niger which 

 have been made by Mr. Charles Ashford, of Christchurch, 

 Hants, shows that there are differences worthy of note. 

 Mr. Ashford has found that the penis-sheath in h. maximus 

 is very constant in its form, the upper part being much 

 enlarged and peculiarly and rigidly flexed or bent upon itself, 

 while in L. cinereo-niger the penis-sheath is longer and of 

 tolerably equal width throughout, in which respect Mr. Ash- 

 ford's figures tally with the one published by Schmidt. The 

 sperm-duct in L. cinereo-niger is only very slightly attached 

 to the oviduct in a part of its length, but in L. maximus 

 moderate force is required to break the attachment. The 

 relative sizes of other parts, as the albumen-gland, the ovo- 

 testis, &c., in sexually mature specimens is constantly different 

 in the two forms. L. cinereo-niger has a larger and less 

 deeply coloured ovo-testis, its average length in three speci- 

 mens from different localities being 29'6 millim., the shortest 

 one being 15 millim., while the greatest length Mr. Ashford 

 has noted in L. maximus is 13 millim. and the average in a 

 number of examples no more than 11 millim. L. cinereo- 

 niger has a smaller and narrower albumen-gland, its average 

 length in the same three specimens being 9'6 millim. and the 

 greatest length noted 13 millim., while in L. maximus the 

 average of sexually mature specimens is 20 millim., that of 

 all, including both mature and immature, 15^ millim. The 

 difference in the point of origin of the retractor muscle of 

 the penis is referred to by Dr. Scharff and corroborated by 

 other writers. 



I am well aware that the differences of the two forms 

 anatomically are not so great nor of such importance as 

 F. Sordelli, whose paper was my authority for the statement 

 1 made in the ' Journal of Conchology ' in 1883, attached to 

 them ; yet that there are differences is quite certain from the 



