70 THE VOYAGE OF H.M.S. CHALLENGEE. 



Milne-Edwards' figures of Gonodactyhts folinii, and as it also fails to agree perfectly with 

 his and Miers' descriptions, it must for the present at least be regarded as a distinct 

 species, differing from Protosquilla {Gonodactyhts) folinii in the following points : — 

 Antero-lateral angles of rostrum simple in Protosquilla folinii, double in Protosquilla 

 elongata. Posterior margin of telson with three rounded spines on each side of the deep 

 median notch in Protosquilla (Gonodactylus) folinii, and a single obtusely rounded lobe 

 in Protosquilla elongata. 



If A. Milne-Edwards' figures are trustworthy the two species also differ in the 

 following features : — First antennas very long in Protosquilla folinii, short in Protosquilla 

 elongata. No spine on anterior edge of basal joint of second antenna in Protosquilla 

 folinii, a long spine in Protosquilla elongata. Carapace nearly as wide as long, 

 rectangular, and with rounded antero- and postero-lateral angles in Protosquilla folinii ; 

 elongated, emarginated, narrow anteriorly, and with antero-lateral angles acute in 

 Protosquilla elongata. Thoracic and abdominal somites rounded in Protosquilla folinii ; 

 lateral margins of thoracic somites of Protosquilla elongata truncated, and postero-lateral 

 angles of abdominal somites acute. 



The species is of great interest as it and the closely related Protosquilla folinii 

 are the most primitive forms which are known among the Stomatopods, exhibiting 

 the embryonic or larval features which are characteristic of the genus, such as the 

 fusion of the telson with the sixth abdominal somite, the small size of the uropods, and 

 the presence of three long spines on the rostrum ; without exhibiting any of the remark- 

 able modifications of the posterior end of the body which are so strikingly characteristic 

 of most of the species of the genus. The telson of an ordinary Squilla, that of Coronis, 

 or that of the most aberrant Protosquilla, such as Protosquilla guerinii, may all be 

 derived from that of Protosquilla folinii by very slight changes, and the carapace of 

 Protosquilla elongata might be readily modified into that of a true Squilla, while it is 

 also very similar to the flat square carapace of the other members of its own genus. 



2. Protosquilla folinii (Milne-Edwards). 



Gonodactylus folinii, A. Milne-Edwards, Obs. sur la Fauna Carcinol. des lies du Cap- Vert, 

 Nouv. Arch. Mus. Hist. Nat., t. iv. 1868, p. 65, pi. xviii. figs. 8-11. 



Gonodactylus Folinii, Miers, E. J., On the Squillida, Ann. and Mag. Nat. Hist., ser. 5, vol. v., 

 1880, p. 123. 



Diagnosis. — Protosquilla with the rostrum ending in a long slender acute 

 median spine, and on each side of this a single acute antero-lateral spine which is directed 

 outwards and forwards and is a little shorter than the median spine. Carapace with 

 rounded antero- and postero-lateral angles. First five abdominal somites smooth, 

 Dorsal surface of sixth abdominal somite with four rounded tubercles, the outer ones 



