Gatty }f urine Laboratory, St, Andrews. I^C 



The first row of hooks is on tlie fifth segment, tlic first 

 two elevations being devoid of them. On tlie fifth the row 

 is at the ])osterior part of the segment at some distance 

 v(Mitrally from the setigerous ])rocess. They increase a 

 little in longtli after the first, and remain nearly the same 

 lor a considerable distance, gradnally, however, becoming 

 elevated so that aljout the twenty-fifth prominent nnci- 

 nigerous processes are formed, and posteriorly they stand 

 out like the "feet" of caterpillars. Toward the tip of the 

 tail they diminish on the narrow segments, and incline 

 ventrall}^ so that those of opposite sides approach, and they 

 cease at tiie last segment. In an example from St. Andrews 

 the uneinigerous processes are irregular posteriorly, being 

 crowded on one side and scantily distributed — even with 

 blanks — on the other, probably from injury. The hooks 

 are arranged in a single row throughout and are smaller 

 than those of Lanice conchUef/a, but more numerous — no less 

 than one hundred and thirty-seven occurring in a row 

 anteriorly, but posteriorly the number diminishes. Each 

 hook in lateral view presents a single tooth above the great 

 fang, though occasionally a minute third is visible. The 

 ])osterior outline is short and has a dimple, whilst the base 

 is elongated and convex iiiferiorly. The anterior outline 

 (below the great fang) is smooth and often slightly convex, 

 and merges into the prow (anterior ])art of the base), which 

 is prolonged as a stout process with a slightly dilated tip, 

 so as to resemble a stud. The occasional occurrence of a 

 isecond tooth above the great fang brings the Heternphenacia 

 rtnouardi of Marion"^, from ^Marseilles, nearer this species. 



Thelepus triserialis, Grube, tlie seventeenth form, is a 

 southern annelid, in which the cephalic collar and the arrange- 

 ment of the parts of the anterior end are similar to those 

 of the foregoing species, but no pigmcnt-spceks remained in 

 the preparations behind the collar, though in life they were 

 jiresent. 



A distinction, however, immediately appears in the bran- 

 chial region, the surface of wliich is more extensive, the 

 filaments more numerous and more slender. Moreover, they 

 arise from three segments, viz., the second, third, and 

 jburth. The first and largest forms a transversely elongated 

 row of filaments on segment 2, its outer g(\\^c passing 

 ventrally considerably below the first bris'.le-tuft behind it. 

 The second springs from the dorsum of the third segment 



* Kevue des Sc. nat. t. iv.. Mavch 1S7*>. 



