Galty Marine Laboratory, St. Andreics. 31 



T. cincinnatus, yet differs iu detail. Thus it is proportionally- 

 larger, the base longer, 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 there are variations in this respect ; moreover, traces 

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

 common. 



The cephalic lobe in the eighteenth species, Grynuea bairdi, 

 Malmgren, is truncate in lateral view, a feature due to the 

 flattened arch of tlie supra-oral fold, which iu many Tere- 

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

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

 nearly vertical. Tlie dorsal collar presents no eye-specks in 

 the preparations, and curves downward to join the supra- 

 oral fokl externally and ventrally. The tentacles agree 

 with those of Thelcpus, being well developed and having a 

 deep groove with frilled margins. 



The general outline of the body agrees with that in 

 Thelepus, though the details diifcr. 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 preparations, 

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

 glandular belt accompanies the sctigerous 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. 



Tlie Norwegian examples appear to be smaller than ours. 



Though Thelepus triserialis agrees with Grymcea bairdi 

 in having three pairs of branchiae, yet their arrangement iu 

 connection with the bristle-tufts differs. 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 sctigerous process, which is like- 

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

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

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

 right it is opposite the second setigerous process. The third 

 is a prominent group oi: 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 



