NASSlDiE. 151 



ster pots, etc., the Nassa itself is frequently caught, attracted 

 thither by odors savor}^ 



Nassa reticulata is said to be very destructive in the oj^ster- 

 parcs of Arcachon (France). It is so numerous that a single 

 tide has yielded 14,600 specimens within a space of 40 French 

 hectares (= about 100 acres). The adult Nassa will bore through 

 the shell of an oyster three years old within eight hours ; but 

 the young shells are far more destructive, because thej^ select the 

 tender shells of the very young oysters, sometimes piercing 

 fifteen or twenty in succession before their hunger is satisfied. 

 An oyster a month old is destroyed in a half-hour. 



According to M. Lespes, N. reticulata is preyed upon by a 

 parasitic Trematode ( Cercaria sagitata) which infests its liver. 

 Its spawn-cases are deposited on the leaves of Zostera and on 

 various other things which are left dr}" only at spring-tides ; the 

 capsules are arranged in rows, and so closely that they overlie 

 each other " like the brass scales of the cheek-band of a hussar" 

 (Johnston). Thej^ are compressed pouches, each of the size of 

 a large spangle, supported on a very short stalk, with a small 

 opening at the top to allow the fry to escape. Mr. Peach has 

 given us some amusing particulars of the fry. These behaved 

 themselves like the fry of other gastropods, skipping about and 

 whirling round by means of their ciliated lobes, apparently in 

 a state of pleasurable excitement ; but it seems that the exercise 

 was compulsory or necessary to prevent the attacks of a swarm 

 of infusoria, which made short work of any tired or feeble infant 

 Nassa. 



The following " subgenera" may be retained as convenient 

 group designations, although the species, varying much in their 

 sculpture, cannot always be positively assigned : 



ARCULARiA, Link, (Eione, Risso.) Body-whorl gibbous on 

 the back ; spire produced ; callus of inner lip greatly extended 

 and covering the spire, N. Thersites^ Brug, Jii, 82, 83), 



NAYTiA, H. and A. Adams. Shell smooth ; aperture with a 

 channel at the hind-part continued up the spire. N. glabrata, 

 Sowb. (lii, 84). 



ALECTRION, Montf, (Mouoccros, Fleming,) Spire elevated, 

 whorls glabrous, polished or papillary; inner lip spreading; 

 outer lip denticulate, not variced externally. N. glans, Linn, 

 (lii, 85), 



ZEUxis, H, and A. Adams. (Telasco, H. and A. Adams, 

 Nassodonta, H. Adams. Zaphon, H. and A. Adams.) Spire 

 elevated, smooth, or longitudinally plicate, polished ; inner lip 

 with the callus defined, or somewhat spreading ; outer lip exter- 

 nally variced, sometimes dentate anteriorly. N. canaliculata^ 

 Lam. (lii, 86, 87). 



Aci CULINA , H. and A. Adams. Shell turreted , polished , smooth , 



