bloomer: on the anatomy of tagelvs. 219 



TageluH gihhus the mantle-lobes are mucli more muscular, while those 

 portions of them posterior to the posterior adductor muscle are not so 

 deep ; the free siphonal tubes, though larger and more muscular, are 

 shorter, and the central part of the proximal portion of the siphon is 

 situated more posteriorly ; the posterior part of the anterior adductor 

 muscle is comparatively larger, but both portions of the muscle 

 are of the same depth. In T. rufus the anterior is deeper than the 

 posterior part, but the division by the ventral integument passing 

 between the two parts is not so marked ; the posterior adductor muscle 

 is smaller ; the foot is more muscular ; the free portion of the pedis 

 retractor posterior muscle is shorter and thicker, and the distal ends 

 of its bifurcations rest on the antero-dorsal surface of the posterior 

 adductor muscle instead of being united with the anterior side as they 

 are in T. rufus. 



Compared with Solecurtus Domheyi (Lam.),^ it will be seen that in 

 T. gibbus the mantle - lobes, anterior to the siphon, are about as 

 muscular, whilst the proximal portion of the siphon is not nearly so 

 muscular, and the free portions of it do not appear to possess the 

 power of inversion like those of S. Domheyi ; the depth of the anterior 

 adductor muscle is not so great, nevertheless the posterior portion is 

 larger ; the foot is not nearly as large or as muscular ; the fi'ee portion 

 of the pedis retractor posterior muscle is much longer, and the posterior 

 part of the animal is also much longer. 



It will thus be inferred from the foregoing that T. gihhus possesses 

 some of the characters of both 1\ rufus and of S. Domheyi, but 

 anatomically lies nearer the latter than the former species. 



Pallial Muscles. — The muscles of the pallial edge commence at the 

 anterior adductor muscle as a deep band and gradually diminish in 

 depth as they proceed posteriorly. 



The anterior adductor muscle (Fig. 1, A. A.) is a muscle of even 

 depth, being about three times as long as deep, with the anterior part 

 slightly curved ventrally. The smaller posterior part is separated 

 from the anterior by the ventral muscular integument passing between 

 them. The muscle is connected anteriorly with the mantle-lobes, and 

 posteriorly with the body-covering and retractor pedis anterior muscles. 



The posterior adductor muscle (Fig. 1, P. A.) is an ovate -shaped 

 muscle connected anteriorly with the body-covering and the bifurcated 

 ends of the retractor pedis posterior muscle, and posteriorly with 

 proximal portions of the siphon and mantle-lobes. 



The musculus cruciformis (Fig. 1, M.C.), as before stated, is 

 situated ventrally to the posterior adductor muscle. The united 

 portion is thick and short, with the four distal ends of nearly 

 equal length. 



The branchial retractor muscles are present, but less prominent and 

 not so well developed as those of Solecurtus strigillatus. 



Pedal Muscles. — The foot (Fig. 1, F.) is deep, short, and very 

 muscular. The general appearance shows it to consist of numerous 



■ On the Anatomy of certain Species of Solenidse " : op. cit., vol. xii (1905), p. 78. 



