Gatty ]\lar!ne Lahorator;/, St. Andrews. lil 



T. cincinnatus, yet dificrs in detail. Thus it is proportionally 

 larj^cr, tiie base louji^cr, the stud at the anterior end of" the 

 base (prow) has a different angle to the outline, is truncated 

 at the tip, and the process beneath is more prominent, 

 though tlierc are variations in tiiis respect ; moreover, traces 

 of a second tooth on the crown above the great fang are 

 common. 



The cephalic lobe in the eighteenth species, Grymoia bairdi, 

 i\Ialingreu, is truncate in lateral view, a feature due to the 

 ilattened arch of the supra-oral fold, which in man}' Tere- 

 bellids forms a spout- or hood-like projection. The surface 

 of the cephalic plate, from which the tentacles arise, is thus 

 nearly vertical. The dorsal collar presents no cye-speeks in 

 the preparations, and curves downward to join the supra- 

 oral fold externally and ventral ly. The tentacles agree 

 with those of Thelc/ms, being well developed and having a 

 deep groove with i'rillcd margins. 



The general outline of the body agrees with that in 

 Thelepus, though the details differ. It is enlarged anteriorly 

 and tapered posteriorly, no example, however, being com- 

 plete. The* dorsal surface is rounded and smoother than 

 in Thelepus, the ventral surface flattened and posteriorly 

 slightly grooved. Anteriorly are ten or eleven glandular 

 ventral shields, which may be wrinkled in the j)reparations, 

 and the outer edges of which touch the rows of hooks. A 

 glandular belt accompanies the setigerous region, but it is 

 not so pronounced dorsally as to form anteriorly the defi- 

 nite edge as in Thelepus, though posteriorly it is well defined. 

 The ventral surface behind the shields is more thinly 

 coated with the glandular tissue, and a thickened median 

 ridge continues for some distance backward. 



The Norwegian examples appear to be smaller than ours. 



Though Thelepus triserialis agrees with Grymoea bairdi 

 in having three pairs of branchiic, yet their arrangement in 

 connection with the bristlc-tufts difl:crs. In the present 

 form a branchial tuft of several filaments occurs on the 

 anterior edge of the second segment, but its attachment is 

 above the line of the first setigerous process, which is like- 

 wise on the second segment. Behind is a second tuft of 

 branchiDe with fewer filaments, and which is in a line with 

 the first setigerous process of the left side, whilst on the 

 right it is oi)posite the sceoiul setigerous process. The third 

 is a prominent group of about six filaments opposite the 

 third bristle-tuft. The individual filaments are similar to 

 those of Thelepus, though in some they are longer, and the 



