THYSANOPODA MONACANTHA. 213 



The maxilliilae (fig. 3a) are still more developed in the directions already 

 indicated in T. crislala. The proximal lobe (1 .) is a little larger than in that 

 species; the distal lobe (l .) expands considerably in breadth from the insertion 

 of the palp to the very broad end, the margin of which is feebly convex with 

 the angles rounded, and the lobe is more than half as broad again as the proxi- 

 mal and considerably broader than long, the length measured to the distal part 

 of the insertion of the palp. The palp (4.) is rather short, not reaching the end 

 of the distal lobe, slender and tapering to the transversely cut end. The pseu- 

 dexopod (px.) is extremely large, twice as long as broad and reaches even a 

 little beyond the end of the distal lobe. 



Ortmann has seen a specimen 32 mm. long. The largest specimen in the 

 Agassiz collection is a female measuring 27 mm., but among the males, measur- 

 ing about 22-24 mm., not a single specimen seems to be adult, as may be judged 

 from the stage of development of the lobes and especially of the processes of the 

 copulatory organs. Fig. 3b and fig. 3c exliibit the two lobes of two males; 

 the spine-shaped process is, as usual in immature specimens, well developed, 

 but the terminal and the lateral processes are simple and slender conical, and 

 the proximal process is nearly similar, yet a little or somewhat curved at the 

 middle. The additional process on fig. 3b is also slender conical, while fig. 3c 

 exhibits a most interesting feature, viz. three additional processes (p .) of the 

 same undeveloped character. I suppose that the existence of three additional 

 processes is a casual anomaly, but the question ought to be studied by a future 

 investigator who has a number of adult males at his disposal. 



Distribution. — This species was established on a specimen taken in the 

 Guinea current in the tropical Atlantic; the Monaco specimen described as T. 

 lateralis is from Lat. 27° 43' N., long. 18° 28' W.; T. denophora Illig from the 

 Gulf of Guinea. T. agassizii Ortm. which, according to my opinion, cannot be 

 separated from T. monacantha, was described from specimens taken in the 

 Gulf of Panama and between the Galapagos and Acapulco; a specimen was 

 captured in the waters of the Hawaiian Islands (Ortmann) and several speci- 

 mens were secured by the "Siboga" in the Indian Archipelago. In the area 

 explored in 1904-1905 the species was not taken in the two most southern dis- 

 tricts or in a broad belt along the coast of South America. I suppose that 

 adult specimens live in considerable depths, at least generally in more than 

 300 fms. from the surface. 



