In a city where so many come and go, something seemed satisfying about the appearance at the National Zoo last week of a member of the third generation of prehensile-tailed porcupines to dwell at the National Zoo.

In a birth announcement issued Friday, the zoo reported that Beatrix, a 2-year-old female, gave birth to what is known as a porcupette.

Birth occurred overnight between Tuesday and Wednesday, the zoo said.

The gender of the youngster was not immediately discernible, according to the zoo, but whether male or female, the baby appears to start the third prehensile-tailed generation in the animal collection on Connecticut Avenue NW. All live together, it appears, in the Small Mammal House.

It was not so long ago that Beatrix, the mother, was herself born at the zoo, to a mother named Bess.

Porcupines are distinguished among animals for their quills.

Indeed the father of the newborn has been named Quillbur, an obvious allusion to one of his species’ principal distinctions.

Among quilled creatures such as porcupines, those described as prehensile-tailed have long, muscular appendages that provide great assistance in grasping, much as we humans make ample use of our distinctive and prehensile thumbs. (But in contrast to thumbs, the tails are not believed to be used to text.)