RHINOCRICUS. 59 
Group IV. SPIROBOLOIDEA. 
Resembling the Iuloidea in general form and structure, but chiefly distinguishable by the following features :— 
The stipites of the gnathochilarium are widely separated proximally by a large undivided triangular 
plate, the mentum. None of the anterior segments are apodous; segments 1-5 bearing each a single 
pair of legs, the 6th with two pairs. No penis is present in the male. The copulatory apparatus is 
completely retractile. 
Fam. SPIROBOLIDA. 
Since the known genera of Spiroboloidea are referred to a single family, the 
characters of the latter are those of the higher group. 
RHINOCRICUS. 
Spirobolus (Rhinocricus), Karsch, Zeitschr. ges. Naturwiss. (3) vi. p. 68 (1881). 
Rhinocricus, Pocock, Journ. Linn. Soc., Zool. xxiv. p. 485 (1893) ; Myriopoda in Max. Weber’s 
Zool. Ergebniss, &c. pp. 889 & 391 (1894). 
Type, Spirobolus (Rhinocricus) parcus, Karsch. 
In 1892 I selected as the type of the genus Lhinocricus the species named parcus, 
which is unknown to me. Since R. parcus was based upon specimens from the island 
of Porto Rico, it is probable that the species resembles in al! essential characters those 
that are referred to Rhinocricus in the following pages, especially those included under 
the headings subordinate to 6! in the analytical key. It is not known whether the 
apical segment of the antenna in &. parcus has many or only a few sensory papille. 
This important feature should, if possible, be ascertained before a generic or subgeneric 
value be assigned, as it probably will be assigned, to the character in question. 
The Central-American species of Rhinocricus known to me have the following 
features in common :— 
Setiferous pores on labrum 242. Eyes widely separated, each consisting of a subcircular cluster of ocelli. 
Lateral portion of first tergal plate widely rounded and not extending inferiorly so low as the inferior 
portion of the second. More or fewer of the segments bearing rear their anterior border, which is 
concealed by the preceding segment, a pair of depressions of unknown function, known as scobine. Each 
scobina consists of a short usually transversely crescentic groove, behind which there is an area of varying 
extent covered with very fine transverse striae. The phallopod of the copulatory apparatus consists of 
two segments, the distal of which terminates in two processes, the smaller and slenderer of which is the 
seminal style, while the stouter, which is laminate at least apically, is the guard. The median unpaired 
sternal or anterior plate of the coleopods is large and subtriangular, with its apex projecting inferiorly 
as low as the inferior end of the anterior or proximal of the two lateral paired lamine. 
Synopsis of the Species examined. 
a. The normal sulcus defining the posterior portion of the terga obsolete 
dorsally, and replaced by a secondary sulcus which lies in front of the 
pore; distal segment of phallopod very short and stout, the seminal style 
slender, and the guard not shorter than the rest of the segment. . . . omiltema, sp. n. 
a‘. The normal sulcus defining the posterior portion of the terga strong or weak 
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