48 CARL BOVALLIUS, AMPHIPODA HYPERIIDEA. I. 2. THAUMATOPSID^E. 



close together in regular rows, ending in hexagonal facets in the surface. Each eye occu- 

 pies a perfect ovate area of the surface of the head. 



The first pair of antenna (PL III, fig. 3 and 4) are long, narrow, straight, almost 

 twice as long as the head (in specimen A. they were broken), measuring 25 mm. in length. 

 The peduncle consists of two joints, the first egg-shaped, three times longer than the 

 second. The first joint of the flagellum is very long and narrow, the dorsal line forming 

 a keel which is finely serrated on the first fourth of the length of the joint. The under-side 

 is widening, somewhat hollowed, fringed with fine, short hairs, which are longer along the 

 first fourth of the length of the joint. The distal end is produced into two triangular teeth. 

 Between these teeth extends the minute, narrow, cylindrical second joint of the flagellum. 



The second pair of antennae are represented by two conical tubercles on the under- 

 side of the head, in front of the mouth-organs. 



The mouth-organs are similar to those in Thaumatops Loveni, and will be de- 

 scribed beloAv. 



The peroson has the segments less high and inflated than in the other species, and 

 also the dorsal keel less distinct. The first two segments reach much deeper down than 

 the following, the first deeper than the second. The first segment is fully as long as 

 half the second, with one spine- like prominence at the hinder corner of the keel, the hinder 

 margins of the segment are smooth without tubercles or denticles. The second segment 

 is the longest of all, armed with two spine-like prominences on the dorsal keel, and a row 

 of small tubercles along the hinder margins. The third to sixth segments are equal in 

 length, armed as the second segment. The seventh is longer than the sixth, but still 

 considerably shorter than the second, armed as the next preceding segments. Along the 

 lower side of the last five segments runs an elevated ridge or keel, which continues along 

 the pleonal, and the first ural segments. This lateral ridge is perfectly smooth on the 

 perseon, but feebly spinulous on the pleon. The peraeon is about 22 mm. in length. 



The epimerals are coalesced with the lateral parts of the corresponding segments. 



The branchial sacks (PI. Ill, fig. 15) exist only on the fourth to sixth pairs of pe- 

 raeopoda, they are shorter than a third of the length of the corresponding femora. 



The first pair of perceopoda (PI. Ill, fig. 5 — 7) equal about a third of the length 

 of the third pair. The femur is longer than the four following joints together, prismatic as all 

 the joints of the peraaopoda; along the anterior, outer margin it is provided with fine, straight, 

 or somewhat curved, long teeth; on the lower part of the hind margin it carries two broad 

 but low teeth; the hinder, lower corner of the joint is produced into a strong, curved 

 tooth. The genu is twice as broad as long, smooth, the hinder lower corner produced 

 into a long, curved tooth, longer than in the preceding joint. The anterior margin of the 

 tibia is very short, the hind margin four times longer, feebly curved, and provided with 

 some few hairs at the apex and a little above. The anterior margin of the carpus is 

 strongly curved, shorter than the anterior margin of the metacarpus, smooth, with a single 

 spine at the lower corner; the carpal process is broad, stout, as long as the rest of the 

 carpus, ending in a strong, sharp tooth, the hind margin has four sharp-pointed teeth, 

 finely serrated at their bases (PI. Ill, fig. G); the front margin is longer than the hind 

 margin of the metacarpus, armed with five strong teeth, finely serrated at their bases as 



