1007.] XATIUAL SCIENCES OF I'll I LADKIJ'IIIA. 413 



111 .1/. tNinits the lirst cii-i-i arc foniietl about as in .1/. bcUiini. Tlie 

 other cirri are eoinparatively more slender, with only three pairs of 

 loufi spines on the front niari>;in of each se<>;nu'nt. and a fourth very 

 minute pair below them. Tlie posterior distal angle of each segment 

 lias one long spine, a shorter one, and usually one or two minute spines 

 (fig. (). 7tii and 8th segments of cirrus V). 



The cirri of .1/. hcUum resemble those of .1/. striatuin. and M. cari- 

 inittni). while those of .1/. viinus are like tlu> cirri of M. gracile as 

 (lescri])ed 1)\- lloek. It will he understood that in comparisons of the 

 cirri the int(>rnie(liato segments are described, unless otherwi.se stated, 

 riu" distal and proximal segments generally have fewer pairs of spines 

 on the front margin. 'Vhr socimkI cirrus usually has additional spincv. 

 variously arranged. 



In .1/. minus the mandible (pi. 31, figs. 7, 8) has four acute teeth, 

 counting the lower point. The space between the upper and second 

 teeth is double that separating the other teeth. Below the lower tooth 

 there is a slender spine representing the lower point developed in most 

 species of Megalasma and Pcecilasma, and shown enlarged in fig. 8. 

 Both upper and lower borders of the mandible have delicate spiny 

 fringes, the spinules in ])art arranged in pairs. The two mandibles are 

 alike in the example dissected. 



The maxilla (pi. 31, fig. 6) has a deep notch below the upper pair of 

 arge spines. Below the notch the edge projects and is closely spinose, 

 as usual. The upper and lower borders are delicately fringed. 



In M. bellum the mandibles (pi. 31, figs. 1, 2, 3, 4) resemble those 

 of M. minus, except in having the lower point split into two teeth (figs. 

 3, 4) on one side of the individual examined, there being therefore five 

 teeth in all. The other mandible of the same individual has the lower 

 point split into foiu- narrow teeth (figs. 1,2). Part of the spines on the 

 surface, near \hv lower points, stand in groups of two or three, as 

 shown in the detail figs. 2 and 4. They also are in groups on the 

 upi^er edge of the mandible, but elsewhere stand singh^ The surface 

 spines are drawn with camera in figs. 2, 4 and S, but in the other figures 

 only the general effect is given. 



The maxilla (pi. 31, fig. 5) resembles that of M. minus, except for the 

 somewhat greater protrusion of the lower part of the spinose edge. 



The hermaphrodite form of .1/. bellum has a long penis, sparsely 

 hairy, with a more profuse bmich of hairs at the distal entl. 



The individual of .1/. minus dissected contained a large egg-mass. 

 The eggs are ovate-piriform, 0.23 mm. long (pi. 31 . fig. 10). 



It will be seen from the above descriptions and figures that while 



