EEPOET ON THE AMPHIPODA. 439 



used for that purpose, as I found the eggs attached to the bases of the first pair of 

 ambulatory legs.'' 



The defimtion of the genus is given as in the "Proceedings," 1873. Willemoes Suhm thinks it 

 nearly related to Phronima, but as " the genital papilla in Thaumops is in the centre of 

 the first thoracic segment, while in Phnmima it is in the seventh body-segment," and for 

 other reasons, he thinks it cannot form a member of the family Phronimidse. In 

 mentioning the seventh body-segment of Phronima, instead of the fifth, he was probably 

 thinking not of the female but of the male. 



Bovallius, 1886, says, "for my part, I am convinced that the .specimen first described as 

 Thaumops pellucida, must be ranged as a distinct species, which still may keep its [specific] 

 name. The males described 1875 (1. c.) [Trans. Linn. Soc] are perhaps identical with 

 Gu<5rin's species and may be placed there, awaiting a closer examination." This point, and 

 others connected with the specific distinctions necessary to be established in this genus, will 

 be more conveniently discussed later on in this Report. 



1874. Willemoes Suhm, Rudolph von. 



Appendix. On the Male and the Structure of Thaumops pellucida. Received 

 October 24, — Read December 11, 1873. Philosophical Transactions of the Royal 

 Society of London. For the year mdccclxxiil Vol. 163. Loudon, mdccclxxiv. 

 pp. 637ff. 



Since the preceding paper was read three males had been caught, the largest " 103 millims. in 

 length, exceeding in length the large female by 19 millims." "These males difi'er from the 

 females by the absence of the genital openings at the base of the first segment and of the 

 breeding lamellae. The two elongate testes begin just behind the caecum of the stomach, and 

 their vasa deferentia run down to the last segment of the pereion, where they terminate by 

 two simple openings between the last pair of pereiopods." "There is not a trace of a 

 second pair of antennae, either in the male or in the female. In the former, however, the 

 first pair of antennae, the five pairs of ambulatory pereiopods, and the caudal appendages 

 are distinguished by the want of the glandular apparatus. In the females these glands 

 cause an enlargement at the top of each of the appendages in question, and this enlargement 

 is of course also wanting in the male." " The mandibles, which at first I thought were 

 entirely wanting, have now been found. They are very much like those of Phronima, only 

 shorter and not so elongate as in that animal; the palpus, which is present in the mandibles 

 of the male Tyjyhidx, could not be detected in Thaumops. The first maxillae are also very 

 small, and differ by their shortness from those of Phronima, but otherwise show the same 

 characters. The second maxilte could not be found with certainty; they are either wanting 

 or represented by an organ which I thought was the labium (Plate L. fig. 6, Jah). This 

 organ arises from the second joint of a very jieculiar appendage, which I have interpreted in 

 my first paper as maxillae (Plate L. fig. 6, ma). I am now satisfied, however, that those are 

 the maxillipeds, consisting of three joints. Two of these joints are united together, the first 

 being attached to the oral apparatus, and the second giving rise to a peculiar organ which 

 consists of two chitinous claws united by a thm layer of the same substance, so as to form 

 a sort of plate. I have already mentioned that I am not quite sure whether this is a labium 

 or, as it seems more probable, the result of the displacement and union of the second 

 maxillae. This organ is situated at the inner side of the maxillipedes, the third joint of 

 which consists of two strongly denticulated and separate claws. The two appendages 

 (Plate XLIX. fig. 1, mx) which I first thought act as maxillce are the gnathopoda of Spence 



