MONOGRAPH OF THE LEUCOSIADÆ. 293 
_ Persephona Lamarckii, Leach, 1. c. p.23. Desmar. l. c. p. 168. 
Guaia punctata, Edw. l, c. p. 197. 
Hab. ad insulas Antillas. 
After a careful collation of the specimens in the British Museum, I have found myself 
compelled to come to the conclusion, that all those which had been designated by Dr. 
Leach as of two distinct species, and named respectively P. Latreillii and P. Lamarckii, 
are in fact specifically identical. "They vary only in a slight degree in the prominence of 
the angular ridge on the pterygostomian region; and even his own specific distinction 
goes no further than the meagre expression, in the one case, “angulis subangulafim dila- 
tatis," and in the other, “ angulis anticis gradatim et obtuse dilatatis." It appears that 
all the specimens which were in the collection at that period were entirely faded, so as to 
have lost that striking and beautiful marking which would have enabled him to identify 
them with Herbst's figure. Browne gives no indication of these markings, either in his 
figure or in the letter-press. It is also remarkable that Leach should have been un- 
aware that those specimens were originally in the Sloanian Collection, and therefore 
brought from the West Indies. As the nomenclature has thus become confused, I have 
ventured to change the specific name; and retaining the generie one given by Dr. Leach, 
have adopted for the species the name Guaia, which Milne-Edwards had applied gene- 
rically. : | 
I find that in this genus, as well as in many others, the relative position of the three 
posterior spines affords a very fixed as well as tangible specific character. In the present 
species, the middle spine is but little higher than the lateral ones, which are very distant ; 
whilst in Lichtensteinii the three are much nearer to each other, and form almost an equi- 
lateral triangle. 
PERSEPHONA LICHTENSTEINII, Leach (Tas. XXXI. fig. 6). Testä orbiculari, angulo ptery- 
gostomiano in dente producto, margine laterali unidentato ; spinis posticis æqualibus, 
medio cum lateralibus triangulum æquilateralem designante. 
Persephona Lichtensteinii, Leach, Zool. Miscell. iii. p. 22. 
Hab. ? Mus. Brit. d et 9. i 
Carapace orbicular, depressed, sparsely granulated; the pterygostomian angie pro- 
duced into a prominent tubercle or tooth; another on the lateral margin on each side ; 
rior spines equal, and so placed as to form the points of an equilateral tri- 
PRET aih straight. External foot-jaws with the pog stalk m 2 
male nearly plain, with only a slight longitudinal groove; in the fe «i wer eep 1y 
grooved towards the inner margin. Anterior legs more slender than in the o : prom 
The arm wholly covered with small tubercles: a line of granules on the vv » eo ^ e 
wrist. The two specimens in the British Museum are a male and a female; unfortunately, 
the abdomen is wanting in each. 
Length of carapace 172 in. 
It is remarkable that the two s imens above referred to in the British E. t P 
the only ones known of this species. Taco yir jid Miscell. petas 
| eae st i * Zoolo ny, 
beyond the meagre definition given by | h in the gl 2 Q 2 
