18 
Psyche 
[March 
weakly demarcated. Legs. Tenent hair well developed, 
with normal clavate apex. Empodial appendage strikingly 
truncate, with one inner lamella excavate apically. Unguis 
with normal four internal teeth, basal pair partially 
joined by an incomplete lamella. Mucro and genital plate. 
Mucro typical of genus. Male genital plate of twelve 
smooth setae. Basal seta pair flattened, blade-like, re- 
mainder slender, acuminate. Clothing. Small underlying 
setae conical and unilaterally eiliate, with short ciliations. 
Discussion: There is considerable variation in the pat- 
tern of this species, as is shown by the figures; however, 
this is less striking than in many species of the genus 
Entomobrya. The external differentiated seta of the labial 
appendage may reach the apex of the same papilla. The 
truncate nature of the labral papillae is not always clear. 
The species has been taken from Southern France, Eng- 
land, and North Africa, but may be widely distributed 
and uncollected elsewhere. 
Distribution: England: Lundy Island; France: Greve 
de Vert, St. Jean Doigt; North Africa: Oued Ykem. 
Mesentotoma laguna (Bacon) 
(New Combination) 
Figs. 11-13 
Entomobrya laguna Bacon, 1913. Jour. Ent. Zool. Clare- 
mont, Calif., 5 :202-204. Bonet, 1934. Eos, 9:157. Essig, 
1942. College Entomology, 83. Gisin, 1944. Verh. 
Naturf. Ges. Basel, 55:71. 
Color and pattern. Pigment gray-brown to gray-blue 
except for appendages which are always blue. Pigment 
generally distributed over body, except for mid-region 
of venter. Many small pale spots scattered over body. 
Explanation of Plate 1 
Characteristic structures of the genus Mesentotoma. Figures 1-7 of 
M. dollfusi: 1-3, various patterns from France; 4, left mucro; 5, hind 
unguis and empodial appendage; 6, external setae of labial appendage; 
7, half of male genital plate (basal seta to right). Figures 8-10 of 
M. exalga : 8, hind unguis and empodial appendage; 9, external setae 
of labial appendage; 10, right mucro. Figures 11-13 of M. laguna : 
11, hind unguis and empodial appendage; 12, right mucro; 13, half of 
male genital plate (basal seta to right). All figures greatly enlarged. 
