THE STOMATOPODA 331 



movable ophthalmic and antennular " somites." Whatever be the 

 morphological value of these segments of the head, there can be no 

 doubt that their separation in the Stomatopoda is a secondary and 

 not a primitive character. 



The movable rostral plate is a character of some interest from 

 its resemblance to that of the Leptostraca ; but it is to be noted 

 that the spiniform rostrum of the larval Stomatopod is not articu- 

 lated, while, on the other hand, the Decapod Rhynchocinetes shows 

 the possibility of the ordinary rostrum becoming divided off by a 

 movable joint from the carapace. 



The lamellar epipodites of the first five pairs of thoracic limbs 

 recall those of the Syncarida ; the bifurcation of the outer flagellum 

 of the antennules is only paralleled among the Caridean Decapods ; 

 the modification of the first pair of pleopods in the male may be 

 compared with that found in the Euphausiacea and the Penaeid 

 Decapods ; the possession of an appendix interna on the pleopods 

 is shared by the Leptostraca and the lower Eucarida. Other 

 characters, such as the structure of the maxilla and the segmenta- 

 tion of the thoracic limbs, cannot be closely compared with those of 

 any other Malacostraca. It seems most probable that the Stomato- 

 poda are a lateral offshoot from the main stem of the Malacostraca, 

 of which, in the absence of connecting links, it is as yet impossible 

 to determine the exact relations. 



The existing Stomatopoda form a very homogeneous group, 

 within which only one family can be recognised, while many of the 

 genera are separated by comparatively slight differences. 



ORDER Stomatopoda, Latreille (1817). 



Family SQDILLIDAE. Squilla, Fabricius (Fig. 186) ; Lysiosquilla, 

 Dana ; Pseudosquilla, Dana ; Gonodactylus, Latreille ; Coronida, Brooks. 



LlTERATUUE. 



1. Bigelow, JR. P. Report upon the . . . Stomatopoda collected by the Steamer 



"Albatross" . . . Proc. U.S. Nat. Mus. xvii. pp. 489-550, 3 pis., 1395. 



2. Brooks, U'. K. Report on the Stomatopoda. Rep. Yoy. "Challenger," 



Zool. xvi. pp. 114, 16 pis., 1886. 



3. Claus, C. Die Metamorphose der Squilliden. Abh. kgl. Ges. Wiss. Gottin- 



gen, xvi. pp. 111-163, 8 pis., 1871. 



4. Die Kreislaufsorgane und Blutbewegung der Stomatopoden. Arb. 



zool. Inst. Wien, v. pp. 1-14, 3 pis., 1883. 



5. Grobben, C. Die Geschlechtsorgane von Squilla mantis, Rond. S. B. Akad. 



Wiss. Wien, Ixxiv. Abth. i. pp. 389-406, 1 pi., 1876. 



6. Hansen, H. J. Isopoden. Cumaceen und Stomatopodtn der Plankton- 



Expedition. Ergeb. Plaukton-Exp. ii. pp. 105, 8 pis., 1895. 



7. Jurich, B. Die Stomatopoden der deutschen Tiefsee-Expedition. Wiss. 



Ergeb. deutschen Tiefsee-Expedition . . . "Valdivia," vii. pp. 361- 

 408, pis. xxv. -xxx., 1904. 



