SPIROBOLELLUS. 87 
6. Anterior lamina of coleopod with its inferior admedian angle produced 
into a distinct apically convex process; tarsi of third to the seventh 
pairs of legs swollen and armed with a minute claw. . . . . . . tylopus, sp. un. 
6’. Anterior lamina of coleopod not produced inferiorly into an admedian 
process ; tarsi of all the anterior legs normal and armed with a strong 
claw. 6 ww ee ee ee ee ee ewe.) eatriculus, Sp. 0. 
1. Spirobolellus richardsoni, sp. n. (Tab. VII. figg. 7 ae.) 
Colour a deep olive-black, with the borders of the first tergal plate, the posterior borders of the other terga 
and the apex of the tail, and the legs ferruginous or yellow; antenne yellow, clouded with fuscous. 
Head smooth, only slightly wrinkled, with 343 labral pores. yes subcircular, widely separated, consisting 
of about seventeen indistinct ocelli. Antenne short. First tergal plate very wide laterally, overlapping 
to a great extent the mandibles and partially also the antenne when lying back in the hollow of the 
mandibles ; the inferior angles rounded; anterior margin wide and defined by a distinct groove. Second 
tergal plate wide inferiorly, where it is largely overlapped by the first, its inferior edge a little produced 
downwards. All the segments from the seventh to the penultimate with their median portion very coarsely 
sculptured from the summit almost down to the legs with larger and smaller close-set subcircular pits ; 
the posterior portion smooth dorsally, somewhat coarsely striate and crested laterally and inferiorly, but 
not so high as the pore, these strie continuous with the pitted sculpturing of the median portion of the 
terga; anterior portion only very finely striolate. ‘lhe transverse sulcus of the terga distinct, but almost 
lost dorsally in the sculpturing; a longitndinal stria present behind the pores. Anal segment with its 
tergal plate less coarsely sculptured than the rest, rugulose, produced posteriorly into a rather wide and 
flat, apically rounded, caudal process which surpasses the summit of the valves; valves with the margins 
neither compressed nor sulcate ; sternal plate with convex posterior border. 
g. Copulatory apparatus as figured on Tab. VII. figg. 76, ¢; the anterior lamina of the coleopod not produced 
inferiorly on the admedian side into a definite process; the posterior lamina subquadrate, not inferiorly 
excavated and divided into two processes; phallopod (Tab. VII. figg. 7d, ¢) forcipate, the proximal 
segment ending in a spatulate process, the distal in a strongly curved slender process opposed to it ; 
between them a slender styliform process. 
Number of segments 45-46. Length of © 56 millim., width about 5°5 millim. 
Hab. Mexico, ‘Tampico in Tamaulipas (Aichardson). 
2. Spirobolellus tylopus, sp.n. (Tab. VII. figg. 8 a-d.) 
Colour (in alcohol) dark slate-grey, with the posterior border of the tergal plates black; head and antenne 
reddish-brown clouded with fuscous; legs almost wholly clear yellow. 
Head with sulcus mesially obsolete, almost smooth; labral pores 2 to 4 on each side. yes composed of about 
20 indistinct ocelli. Antenne slightly incrassate, the segments subequal in length. Furst tergal plate much 
narrower laterally than in S. richardsoni and not concealing the mandible, extending, however, at least as 
low as the second; its anterior border somewhat widely emarginate, defined by a groove which passes from 
the level of the eye down and back to the postero-lateral angle, which is obtuse ; antero-lateral angle 
rounded. Remaining segments without any definite transverse sulcus, but marked with a shallow 
depression which passes from side to side, over the segment behind the pores ; posterior portion laterally 
longitudinally striate about halfway up to the pores, and irregularly striolate and feebly sculptured 
dorsally behind the smooth posterior margin; median portion much more definitely and coarsely 
sculptured or pitted with short transverse shallower and deeper grooves, frequently crescentic in shape ; 
anterior portion not distinctly striate transversely. Anal segment with the tergal plate not produced 
into a caudal process, convex, scarcely even angled, although covering the summit of the valves; valves 
smooth, with margins unthickened and not in any way compressed ; sternal plate obtusely triangular. 
3. Smaller than @, with seventh segment expanded. Legs of first and second pairs normal, with slender 
