LOCUST SCREW. 151 



sandy bottoms, we see many little grey shrimp-like 

 creatures, with thick-set arching bodies, which swim 

 rapidly, and with much vibration of the abdominal feet, 

 from weed to weed. If we catch one and lay it on the 

 rock or on the wet sand, it appears very helpless, for 

 its vertically thin shape and arched attitude preclude 

 the possibility of its crawling : it falls upon its side, 

 and vainly struggles round and round as on a pivot, or 

 makes aimless jerks by throwing out the tail. It is of 

 a greenish blue, or glaucous colour, marked with red 

 dots. This is the common Locust Screw, 1 which is so 

 confined to sea-water, that it has been affirmed that if 

 put into fresh water it presently dies. But the experi- 

 ments of Mr. Eobertson negative this statement : 2 he 

 has found that five out of seven, after being eighteen 

 hours in rain-water, continued to live upon being re- 

 turned to salt water. 



I delight to trace the manifestations of parental love 

 in these tiny forms of animal life. It had long been 

 known that the females of this species display a solici- 

 tude for their infant offspring, which they carry for 

 some time about with them ; but the following very 

 pleasing details of maternal manners have recently been 

 observed by my relative, Dr. James Salter, and by him 

 communicated to the learned zoologists who are now 

 engaged upon the history of this order : 



1 Gammarus lonista. 2 Bate and Westwood's Crv^tacea, p. 382. 



