248 Part III. — Twenty-second Annual Report 



Genus Thaumalsus Kroyer, 1849. 



Thaumaleus thomsoni, Giesb. PI. xiv., fig. 1-4. 



1892. Thaumaleus thomsoni, Giesb., Pelag. Copep. des Golfes v. 



Neapel, p. 584, pi. 46, fig. 7, 27, 31, 36, 40. 

 1902. Thaumaleus thompsoni, Scott, 20th Ann. Rept. Fishery 



Board for Scotland, pt. iii., p. 470, pi. xxv., fig. 5, 6. 



In Part III. of the Twentieth Annual Report of the Fishery Board 

 for Scotland, I published a description with figures of the male of 

 Thaumaleus thompsoni taken in Lerwick Harbour, Shetland. Recently, 

 Avhen examining a small collection of Monstrillas that had been captured 

 from time to time during the past twelve or fifteen years, I found a single 

 female of the same species that had been taken in a tow-net sample 

 collected off Scarborough on July 9, 1893, during some investigations on 

 behalf of the Fishery Board for Scotland ; this specimen I will now 

 briefly describe, and illustrate the description with figures showing a few 

 of its more characteristic features. 



The specimen referred to was elongated and very slender, and 

 measured 4-8 mm. in length (about i of an inch). The cephalothoracic 

 segment was about equal to twice the entire length of tlae remaining 

 segments of the thorax and abdomen combined (fig. 1, pi. xiv.). 



The antennules are short and stout, and appear to consist of four 

 joints ; but the third, which is small, seems to be partly coalescent with 

 the second (fig. 2, pi. xiv.). 



The fifth pair of thoracic feet are moderately large, foliaceous, and are 

 abruptly wider at the distal extremity, the result of a lobe-like process 

 on the inner distal aspect ; each foot carries three apical setre, the 

 innermost of which is considerably shorter than the other two, as shown 

 in the drawing (fig. 3, pi. xiv.). 



The abdomen consists of two segments ; the first is fully half as long 

 as the last segment of the thorax, and larger and more dilated than the 

 second segment. The short furcal joints carry three moderately elongated 

 setae (tig. 4, pi. xiv.). 



The structure of the fifth pair of thoracic feet, and the form of the 

 abdomen referred to above, seem to be characteristic of this species. 



Thaumaleus rigidiis (I. C. Thompson). PI. xiii., fig. 15-17; pi. xiv, fig. 19. 



1888. Cymbasoma rigida, I. C. Thompson. Linn. Soc. Journ. 



Zool., vol. XX., p. 154, pi. xiii., fig. 1-4. 

 1890. Monstr ilia rigida, Bourne. Quart. Journ, Micros. Science, 



vol. XXX., pi. xxxvii., fig. 8, 11, 12. 

 1892. Thaiimaleus claparklii, Giesb., op. cit., pp. 381-385, taf. 



46, fig. 5, 15, 21, 26. 



Description of the Female. — Length of the specimen represented by 

 the drawing (fig. 15, pi. xiii.), 2*7 mm. (^ of an inch). The cephalothorax 

 is moderately stout, rather wider near the anterior end, and nearly twice as 

 long as the entire length of the remaining segments. The abdomen is 

 composed of two segments , the first is about one and a half times the 

 length of the last segment of the thorax, and the proximal half is more or 

 less dilated ; the second segment, which is smaller than the first, is 

 probably composed of two coalescent segments, as a slight constriction, 

 dividing the segment into two portions as shown by the drawing (fig. 15, 

 pi. xiii., and fig. 19, pi. xiv.), is observable in all the specimens examined. 



The antennules are short and stout and appear to be four-jointed, the 

 first and third joints being very small (fig. 16, pi. xiii.). 



