288 A HISTORY OF EECENT CEUSTACEA 



long spines symmetrically arranged, while the preceding- 

 segment, which in the other species has some rather 

 inconspicuous carinse, here has about fifty-six long cylin- 

 drical spines, ' each of which ends in a blunt rounded tip 

 with a perforation from which a soft tubular fleshy process 

 protrudes.' 



Leptosquilla, Miers, 1880, is defined as having the 

 ' ophthalmic segment greatly elongated ; rostrum not 

 reaching beyond half the length of this segment,' and to 

 it is assigned the single species Leptosquilla Schmeltzii 

 (A. Milne-Edwards), from the Samoa Islands. 



For a history of the development of the Stomatopoda 

 the foundation was laid by Dr. Glaus in 1871. Many 

 additions have been made and much precision given to 

 the knowledge of this subject by the researches of Pro- 

 fessor Brooks. The transparent pelagic larvas are fre- 

 quently captured, and in consequence of their glass-like 

 clearness the individual organisms can be easily studied, 

 but there are special difficulties connected with tracing 

 the series of changes which they pass through between 

 the egg and the adult condition. Unlike most Malaco- 

 straca, the Squillidas do not carry their eggs about with 

 them, but deposit them in their deep burrows, there to be 

 aerated by the currents of water which the pleopods of the 

 parent maintain. Hence the hatching of eggs in an 

 aquarium has not yet been brought about. The older 

 larvae are hardy, but seldom found near the shore. The 

 younger larvse can be found near the shore, but seldom 

 moult in confinement. The life-history has, therefore, to 

 be traced by a comparison of numerous forms collected 

 from the open sea, and here there is a twofold risk, of 

 uniting the larvee of quite distinct animals as stages in 

 the life-history of a single species, and of disuniting the 

 larval stages of a single species as though they belonged 

 to distinct species or even distinct genera. In this laby- 

 rinth the explorer has to be guided in part by general 

 resemblances, but more especially by comparative measure- 

 ments. Professor Brooks, having obtained a number of 

 specimens which by general resemblance seemed to make 



