THE ANATOMY OF M KCJAL ATKACTUS — KKS TliVKN". 443 



"It is obvious from the l)ullv of tlio larval shell that M. 

 arnamts can have no free-s\viiuniiii<^ stage."* A careful study of 

 this protocoiich has led iiic to coiiclufle that the latter -svliorlsare 

 neanic, the thiuil)le-sha[)e(l cap prol)aljly veliger structure. 1 have 

 discussed the stages of growth represented by the tirst of these 

 protoconchs more fully in a paper on "The Ontogenetic stages 

 represented b}' the Gasteropod Protoconch," now in the press. 



Of the operculum, it is almost sufficient to say that it is of the 

 fusoid type. There is, perhaps, a closer resemblance to the 

 Turbiuellid operculum than to an}' of the many others of this 

 type. 



In the absence of a snout, and the position of the tentacles and 

 tentacle lobe, Mfyalatractus resembles Fasciolaria Jilarnenlosa, 

 Lamk., as figured by Quoy and Gaimard.f In this resj^ect it 

 differs ivomJ/i'hn(^ena(^"Pt/)-ula")tHb<i, Lamk., which is figured by 

 Souleyet| as having a very long snout. 



It agrees with J/, taba in the development of the Itypobranchial 

 jnucous gland, the form of osphradium, and ctenidium ; in the 

 possession of a well developed mucous (?) groove along the front 

 margin of the foot ; in the position of the vas-deferens on the 

 body, and the point of attachment of the penis ; the last organ, 

 however, is larger in our genus than in Souleyet's example. A 

 description of the hypobranchial gland of Fasciolaria tulipa by 

 F. Bernard§ is, in the main, equallj^ applicable to our first species, 

 M. aruanus ; whilst the osphradium is similar to that of Cassi- 

 daria, as described by the same writer.|| 



I can find no description of a proboscideal complex which 

 resembles that of our genus; that of Fyrida ficus (Linn?), as 

 described by Amadrut,^ being that which perhaps most nearly 

 approaches the arrangement obtaining in Megcdatr actus. In that 

 species we find a proboscis-sheath, "le trocart," and sac, which, 

 however, this author terms "la gaine '"' ; but the proboscis, 

 instead of lying simply coiled up in the sac, is invaginated into 

 itself, and so lies in that cavity as an irregularly pyriform mass. 

 The complex of Melongena tuba is probably the same as that of 

 Megalatractiis. The proboscis is very long, and is represented by 

 Souleyet as lying coiled up in the body cavit}^ when retracted.** 

 I find it hard to understand these drawings, and it seems 

 possible that they are somewhat incorrect. If they are 

 correct, then no portion of the proboscis is invaginable or 

 evaginable. There is only a short length of the cesophagus 



* Hedley— Proc. Linn. Soc. N.S. Wales, xxv., 1900, p. 508. 

 + Quoy and Gaimard — Voy. " L' Astrolabe," Atlas, pi. 35, f. 2. 

 X Souleyet— Zool. '-Bonite," ii., 1S52, Atlas, pi. 43. 

 § Bernard— Ann. Sci. Nat., (7), ix., 1890, p. 337. 

 II Bernard— Xoc. cit., p. 140. 



^ Amadrut— Ann. Sci. Nat., (S), vii., 1S9S, p. 20. 

 ** Souleyet— Zool. " Bonite," 1852, Atlas, pi. 43, f. 5 and 6. 



