a couple among the typical spécimens of T. acutifrons, Holt & 

 Tatt., belong to the same form ; they were taken in the Atlantic 

 west of Ireland. It may be useful to add some remarks to m y 

 earlier description. 



Adult spécimens of T. distinguenda measure generally 

 2o-23 mm ; a single unusually large female spécimen measures 

 l5 mm in length. Half-grown or a little larger spécimens of 

 T. acutifrons are thus as long as adult spécimens of T. distin- 

 guenda) I will therefore point out the différences between such 

 spécimens of the same length of both species. The integuments 

 of the body are a little more flrmly chitinized in T. distinguenda 

 than in T. acutifrons. The front margin of the carapace in 

 T. distinguenda is shaped about as in adult spécimens of T. 

 acutifrons, having the major distai part of each half a little 

 convex, the terminal angle measuring about iio°, and the tip 

 adorned with a tiny tooth directed considerably or nearly ver- 

 tically upwards, while half-grown spécimens of T. acutifrons 

 — as mentioned above — have the front part of the carapace 

 more produced, the distal angle smaller, etc. The eyes are 

 darker and distinctly smaller in T. distinguenda than in young 

 spécimens of the same length of T. acutifrons. The lobe from 

 first antennular joint differs sharply in one particular : in T. 

 distinguenda the terminal process is, seen from the side, some- 

 what or considerably longer than deep, with its distal part very 

 slender, spiniform (in spécimens not very well preserved this 

 spiniform end is sometimes mutilated); in half-grown spéci- 

 mens of T. acutifrons this process is generally shorter than, 

 sometimes at the most as long as, deep. 



Thysanopoda pectinata, Ortm. 



Thysanopoda pectinata, Ortmann, op. cit., p. 10, Pl. i, fig., 4, 

 (not T. pectinata, H. J. H.) 



Description. — A single somewhat mutilated large spécimen 

 is at hand. — The anterior part of the carapace differs mue h 

 from that in T. acutifrons ; seen from above it is considerably 

 produced but not tnangular, because the front end is broad 

 and very obtuse, while the latéral margins of the part produced 



(42) 



